Unrated severityNVD Advisory· Published May 28, 2026

CVE-2026-46123

Description

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: virtio_bt: clamp rx length before skb_put

virtbt_rx_work() calls skb_put(skb, len) where len comes directly from virtqueue_get_buf() with no validation against the buffer we posted to the device. The RX skb is allocated in virtbt_add_inbuf() and exposed to virtio as exactly 1000 bytes via sg_init_one().

Checking len against skb_tailroom(skb) is not sufficient because alloc_skb() can leave more tailroom than the 1000 bytes actually handed to the device. A malicious or buggy backend can therefore report used.len between 1001 and skb_tailroom(skb), causing skb_put() to include uninitialized kernel heap bytes that were never written by the device.

The same path also accepts len == 0, in which case skb_put(skb, 0) leaves the skb empty but virtbt_rx_handle() still reads the pkt_type byte from skb->data, consuming uninitialized memory.

Define VIRTBT_RX_BUF_SIZE once and reuse it in alloc_skb() and sg_init_one(), and gate virtbt_rx_work() on that same constant so the bound checked matches the buffer actually exposed to the device. Reject used.len == 0 in the same gate so an empty completion can no longer reach virtbt_rx_handle().

Use bt_dev_err_ratelimited() because the length value comes from an untrusted backend that can otherwise flood the kernel log.

Same class of bug as commit c04db81cd028 ("net/9p: Fix buffer overflow in USB transport layer"), which hardened the USB 9p transport against unchecked device-reported length.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

In the Linux kernel's virtio_bt driver, a missing length check allows a malicious virtio device to expose uninitialized kernel heap memory by reporting a size larger than the buffer.

Vulnerability

In the Linux kernel's Bluetooth virtio_bt driver, the function virtbt_rx_work() calls skb_put(skb, len) where len is obtained from virtqueue_get_buf() without validation against the actual buffer size. The RX skb is allocated in virtbt_add_inbuf() and exposed to the device as exactly 1000 bytes via sg_init_one(). However, alloc_skb() can allocate more tailroom, so a malicious or buggy backend can report used.len between 1001 and skb_tailroom(skb), causing skb_put() to include uninitialized kernel heap bytes. Additionally, a zero length leaves the skb empty, but virtbt_rx_handle() reads pkt_type from skb->data, consuming uninitialized memory. All Linux kernel versions with virtio_bt prior to the fix are affected.

Exploitation

An attacker with control over the virtio device (e.g., a malicious hypervisor or guest) can send crafted buffer lengths via the virtqueue. No authentication is required; the attacker must be able to interact with the virtio layer. The device reports a used.len value larger than the actual data or zero. The kernel driver then processes this without validation, leading to exposure or corruption of kernel heap memory.

Impact

Successful exploitation leads to information disclosure (leak of uninitialized kernel heap memory) and potentially denial-of-service or further memory corruption. The attacker can read sensitive kernel heap data. The vulnerability has a high severity due to the potential for leaking secrets.

Mitigation

The fix is committed in Linux kernel commit 6c1730099a6fc18b183bd6c1adad3b54adcaeda9 [1]. The patch defines VIRTBT_RX_BUF_SIZE and uses it consistently to clamp the length, and rejects zero length. Users should update to a kernel version containing this fix. If not patched, restrict access to the virtio device to trusted entities.

References

Making sure you're not a bot!

AI Insight generated on May 28, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected products

Ubuntu/Linux Kernelllm-fuzzy

Patches

e6b4296f170d

Bluetooth: virtio_bt: clamp rx length before skb_put

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitMichael BommaritoApr 21, 2026Fixed in 7.0.7via kernel-cna

commit

2 files changed · +24 −10

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 76d61af8a275e9..2c5c39356a1c81 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 76d61af8a275e9..2c5c39356a1c81 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

21bd244b6de5

Bluetooth: virtio_bt: clamp rx length before skb_put

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitMichael BommaritoApr 21, 2026Fixed in 7.1-rc3via kernel-cna

commit

2 files changed · +24 −10

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 76d61af8a275e9..2c5c39356a1c81 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 76d61af8a275e9..2c5c39356a1c81 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

6c1730099a6f

Bluetooth: virtio_bt: clamp rx length before skb_put

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitMichael BommaritoApr 21, 2026Fixed in 6.12.88via kernel-cna

commit

2 files changed · +24 −10

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 756f292df9e87d..3fe17539b4ba54 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 756f292df9e87d..3fe17539b4ba54 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

ed41c81d30b2

Bluetooth: virtio_bt: clamp rx length before skb_put

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitMichael BommaritoApr 21, 2026Fixed in 6.6.140via kernel-cna

commit

2 files changed · +24 −10

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 18208e152a3675..af1775d04860b2 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 18208e152a3675..af1775d04860b2 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

b40cdd1b1370

Bluetooth: virtio_bt: clamp rx length before skb_put

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitMichael BommaritoApr 21, 2026Fixed in 6.18.30via kernel-cna

commit

2 files changed · +24 −10

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 6f1a37e85c6a47..3a0f6715cd9944 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 6f1a37e85c6a47..3a0f6715cd9944 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

e6b4296f170d

Bluetooth: virtio_bt: clamp rx length before skb_put

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gitMichael BommaritoApr 21, 2026via nvd-ref

commit

2 files changed · +24 −10

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 76d61af8a275e9..2c5c39356a1c81 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 76d61af8a275e9..2c5c39356a1c81 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

ed41c81d30b2

Bluetooth: virtio_bt: clamp rx length before skb_put

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gitMichael BommaritoApr 21, 2026via nvd-ref

commit

2 files changed · +24 −10

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 18208e152a3675..af1775d04860b2 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 18208e152a3675..af1775d04860b2 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

b40cdd1b1370

Bluetooth: virtio_bt: clamp rx length before skb_put

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gitMichael BommaritoApr 21, 2026via nvd-ref

commit

2 files changed · +24 −10

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 6f1a37e85c6a47..3a0f6715cd9944 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 6f1a37e85c6a47..3a0f6715cd9944 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

21bd244b6de5

Bluetooth: virtio_bt: clamp rx length before skb_put

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gitMichael BommaritoApr 21, 2026via nvd-ref

commit

2 files changed · +24 −10

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 76d61af8a275e9..2c5c39356a1c81 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 76d61af8a275e9..2c5c39356a1c81 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

6c1730099a6f

Bluetooth: virtio_bt: clamp rx length before skb_put

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gitMichael BommaritoApr 21, 2026via nvd-ref

commit

2 files changed · +24 −10

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 756f292df9e87d..3fe17539b4ba54 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

drivers/bluetooth/virtio_bt.c+12 −5 modified

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 756f292df9e87d..3fe17539b4ba54 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -12,6 +12,7 @@
 #include <net/bluetooth/hci_core.h>
 
 #define VERSION "0.1"
+#define VIRTBT_RX_BUF_SIZE 1000
 
 enum {
 	VIRTBT_VQ_TX,
@@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
 	struct sk_buff *skb;
 	int err;
 
-	skb = alloc_skb(1000, GFP_KERNEL);
+	skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
-	sg_init_one(sg, skb->data, 1000);
+	sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE);
 
 	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
 	if (err < 0) {
@@ -227,8 +228,15 @@ static void virtbt_rx_work(struct work_struct *work)
 	if (!skb)
 		return;
 
-	skb_put(skb, len);
-	virtbt_rx_handle(vbt, skb);
+	if (!len || len > VIRTBT_RX_BUF_SIZE) {
+		bt_dev_err_ratelimited(vbt->hdev,
+				       "rx reply len %u outside [1, %u]\n",
+				       len, VIRTBT_RX_BUF_SIZE);
+		kfree_skb(skb);
+	} else {
+		skb_put(skb, len);
+		virtbt_rx_handle(vbt, skb);
+	}
 
 	if (virtbt_add_inbuf(vbt) < 0)
 		return;
-- 
cgit 1.3-korg

Vulnerability mechanics

Root cause

"Missing validation of device-reported length in virtbt_rx_work() allows skb_put() to consume uninitialized kernel heap memory."

Attack vector

An attacker controlling a malicious or buggy virtio Bluetooth backend can report a `used.len` value outside the valid range [1, 1000] when completing a receive buffer. If the backend reports a length between 1001 and `skb_tailroom(skb)`, `skb_put()` includes uninitialized kernel heap bytes that were never written by the device, leading to an information disclosure. If the backend reports `len == 0`, `virtbt_rx_handle()` reads the `pkt_type` byte from uninitialized `skb->data`, also consuming uninitialized memory [patch_id=2898502]. No authentication is required; the attacker only needs control over the virtio device (backend) side.

Affected code

The vulnerability resides in `drivers/bluetooth/virtio_bt.c` in the `virtbt_rx_work()` function. The RX skb is allocated in `virtbt_add_inbuf()` and exposed to the virtio device as exactly 1000 bytes via `sg_init_one()`, but the length returned by `virtqueue_get_buf()` was used directly in `skb_put()` without validation against that buffer size [patch_id=2898502].

What the fix does

The patch introduces a `VIRTBT_RX_BUF_SIZE` constant (1000) and uses it consistently in both `alloc_skb()` and `sg_init_one()` so the buffer exposed to the device matches the allocation. In `virtbt_rx_work()`, a guard clause rejects `len == 0` and `len > VIRTBT_RX_BUF_SIZE`, dropping the skb and logging a rate-limited error instead of passing the unchecked length to `skb_put()`. This ensures the bound checked matches the actual buffer size handed to the device and prevents both the heap over-read and the uninitialized-memory read on zero-length completions [patch_id=2898502].

Preconditions

configAttacker must control or compromise the virtio Bluetooth backend device
inputThe virtio_bt driver must be loaded and receiving buffers from the backend

Generated on May 28, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.

References

News mentions

No linked articles in our index yet.

cvss	0.000
epss	0.000
exploit	0.000
kev	0.000
patch	-0.070
ransomware	0.000