Unrated severityNVD Advisory· Published May 28, 2026

CVE-2026-46133

Description

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

RDMA/rxe: Reject unknown opcodes before ICRC processing

Even after applying commit 7244491dab34 ("RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv"), a single unauthenticated UDP packet can still trigger panic. That patch handled payload_size() underflow only for valid opcodes with short packets, not for packets carrying an unknown opcode. The unknown-opcode OOB read described below predates that commit and reaches back to the initial Soft RoCE driver.

The check added there reads

pkt->paylen < header_size(pkt) + bth_pad(pkt) + RXE_ICRC_SIZE

where header_size(pkt) expands to rxe_opcode[pkt->opcode].length. The rxe_opcode[] array has 256 entries but is only populated for defined IB opcodes; any other entry (for example opcode 0xff) is zero-initialized, so length == 0 and the check degenerates to

pkt->paylen < 0 + bth_pad(pkt) + RXE_ICRC_SIZE

which does not constrain pkt->paylen enough. rxe_icrc_hdr() then computes

rxe_opcode[pkt->opcode].length - RXE_BTH_BYTES

which underflows when length == 0 and passes a huge value to rxe_crc32(), causing an out-of-bounds read of the skb payload.

Reproduced on v7.0-rc7 with that fix applied, QEMU/KVM with CONFIG_RDMA_RXE=y and CONFIG_KASAN=y, after

rdma link add rxe0 type rxe netdev eth0

A single 48-byte UDP packet to port 4791 with BTH opcode=0xff and QPN=IB_MULTICAST_QPN triggers:

BUG: KASAN: slab-out-of-bounds in crc32_le+0x115/0x170 Read of size 1 at addr ... The buggy address is located 0 bytes to the right of allocated 704-byte region Call Trace: crc32_le+0x115/0x170 rxe_icrc_hdr.isra.0+0x226/0x300 rxe_icrc_check+0x13f/0x3a0 rxe_rcv+0x6e1/0x16e0 rxe_udp_encap_recv+0x20a/0x320 udp_queue_rcv_one_skb+0x7ed/0x12c0

Subsequent packets with the same shape fault on unmapped memory and panic the kernel. The trigger requires only module load and "rdma link add"; no QP, no connection, and no authentication.

Fix this by rejecting packets whose opcode has no rxe_opcode[] entry, detected via the zero mask or zero length, before any length arithmetic runs.

AI Insight

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

A single unauthenticated UDP packet with an unknown opcode can cause an out-of-bounds read in the Linux kernel's Soft RoCE driver, leading to a kernel panic.

Vulnerability

In the Linux kernel, the RDMA/rxe (Soft RoCE) driver fails to properly validate opcodes before ICRC processing. The rxe_opcode[] array has 256 entries but only populated for defined IB opcodes; unknown opcodes (e.g., 0xff) have zero length, causing header_size(pkt) to return 0. The check pkt->paylen < header_size(pkt) + bth_pad(pkt) + RXE_ICRC_SIZE then degenerates, allowing an out-of-bounds read in rxe_icrc_hdr() which computes rxe_opcode[pkt->opcode].length - RXE_BTH_BYTES (underflow). This affects kernel versions up to v7.0-rc7, including the fix from commit 7244491dab34.

Exploitation

An unauthenticated remote attacker can trigger the vulnerability by sending a single 48-byte UDP packet to UDP port 4791 with BTH opcode=0xff and QPN=IB_MULTICAST_QPN. No QP setup, connection, or authentication is required; only the module must be loaded (CONFIG_RDMA_RXE=y) and a link added (e.g., rdma link add rxe0 type rxe netdev eth0). The packet causes rxe_icrc_hdr() to compute a huge length, leading to an out-of-bounds read in crc32_le().

Impact

A successful exploit results in a slab-out-of-bounds read via KASAN, leading to kernel panic or crash. Repeated packets can cause the kernel to panic on unmapped memory, resulting in denial of service. Potential information disclosure may occur from the out-of-bounds read, but no code execution is described.

Mitigation

The fix is included in commit e3dc3a2fb05f ("RDMA/rxe: Reject unknown opcodes before ICRC processing"), which adds proper opcode validation. The patch is available at [1]. Users should update to a kernel containing this commit. No workarounds are known; disabling the RDMA/rxe driver if not needed may reduce exposure.

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

006a3a5f7534

RDMA/rxe: Reject unknown opcodes before ICRC processing

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitMichael BommaritoApr 14, 2026Fixed in 6.18.30via kernel-cna

commit

2 files changed · +22 −2

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

f8ee926431a7

RDMA/rxe: Reject unknown opcodes before ICRC processing

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitMichael BommaritoApr 14, 2026Fixed in 6.12.88via kernel-cna

commit

2 files changed · +22 −2

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

6fa18025e578

RDMA/rxe: Reject unknown opcodes before ICRC processing

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitMichael BommaritoApr 14, 2026Fixed in 7.0.7via kernel-cna

commit

2 files changed · +22 −2

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

4c6f86d85d03

RDMA/rxe: Reject unknown opcodes before ICRC processing

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitMichael BommaritoApr 14, 2026Fixed in 7.1-rc3via kernel-cna

commit

2 files changed · +22 −2

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

e3dc3a2fb05f

RDMA/rxe: Reject unknown opcodes before ICRC processing

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitMichael BommaritoApr 14, 2026Fixed in 6.6.140via kernel-cna

commit

2 files changed · +22 −2

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

f8ee926431a7

RDMA/rxe: Reject unknown opcodes before ICRC processing

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gitMichael BommaritoApr 14, 2026via nvd-ref

commit

2 files changed · +22 −2

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

6fa18025e578

RDMA/rxe: Reject unknown opcodes before ICRC processing

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gitMichael BommaritoApr 14, 2026via nvd-ref

commit

2 files changed · +22 −2

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

006a3a5f7534

RDMA/rxe: Reject unknown opcodes before ICRC processing

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gitMichael BommaritoApr 14, 2026via nvd-ref

commit

2 files changed · +22 −2

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

e3dc3a2fb05f

RDMA/rxe: Reject unknown opcodes before ICRC processing

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gitMichael BommaritoApr 14, 2026via nvd-ref

commit

2 files changed · +22 −2

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

4c6f86d85d03

RDMA/rxe: Reject unknown opcodes before ICRC processing

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.gitMichael BommaritoApr 14, 2026via nvd-ref

commit

2 files changed · +22 −2

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

drivers/infiniband/sw/rxe/rxe_recv.c+11 −1 modified

diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
index f79214738c2b86..2d5e701ff961af 100644
--- a/drivers/infiniband/sw/rxe/rxe_recv.c
+++ b/drivers/infiniband/sw/rxe/rxe_recv.c
@@ -330,6 +330,17 @@ void rxe_rcv(struct sk_buff *skb)
 	pkt->qp = NULL;
 	pkt->mask |= rxe_opcode[pkt->opcode].mask;
 
+	/*
+	 * Unknown opcodes have a zero-initialized rxe_opcode[] entry, so
+	 * both mask and length are 0.  Reject them before any length math:
+	 * rxe_icrc_hdr() would otherwise compute length - RXE_BTH_BYTES
+	 * and pass the underflowed value to rxe_crc32(), producing an
+	 * out-of-bounds read.
+	 */
+	if (unlikely(!rxe_opcode[pkt->opcode].mask ||
+		     !rxe_opcode[pkt->opcode].length))
+		goto drop;
+
 	if (unlikely(pkt->paylen < header_size(pkt) + bth_pad(pkt) +
 		       RXE_ICRC_SIZE))
 		goto drop;
-- 
cgit 1.3-korg

Vulnerability mechanics

Root cause

"Missing validation of unknown InfiniBand opcodes before ICRC length arithmetic allows an integer underflow that leads to an out-of-bounds read."

Attack vector

An unauthenticated attacker sends a single 48-byte UDP packet to port 4791 with a BTH opcode field set to an undefined value (e.g. 0xff) and QPN set to `IB_MULTICAST_QPN`. The existing length check `pkt->paylen < header_size(pkt) + bth_pad(pkt) + RXE_ICRC_SIZE` degenerates because `header_size()` returns 0 for unknown opcodes, failing to constrain `paylen`. The subsequent call to `rxe_icrc_hdr()` computes `rxe_opcode[pkt->opcode].length - RXE_BTH_BYTES`, which underflows (0 - 12) and passes a huge value to `rxe_crc32()`, causing an out-of-bounds read of the skb payload. No QP, connection, or authentication is required; only the Soft RoCE module must be loaded and an rxe device added.

Affected code

The vulnerable function is `rxe_rcv()` in `drivers/infiniband/sw/rxe/rxe_recv.c`. The `rxe_opcode[]` array has 256 entries but only defined IB opcodes are populated; any other entry (e.g. opcode 0xff) is zero-initialized, so `length == 0` and `mask == 0`.

What the fix does

The patch adds a new early check in `rxe_rcv()` immediately after `pkt->mask |= rxe_opcode[pkt->opcode].mask`. It tests whether either `rxe_opcode[pkt->opcode].mask` or `rxe_opcode[pkt->opcode].length` is zero; if so, the packet is dropped via `goto drop`. This rejects unknown opcodes before any length arithmetic or ICRC processing occurs, preventing the integer underflow in `rxe_icrc_hdr()` that led to the out-of-bounds read. The check is placed before the existing `paylen` validation so that unknown opcodes are caught regardless of packet size.

Preconditions

configThe Soft RoCE (RXE) module must be loaded (CONFIG_RDMA_RXE=y) and an rxe device must be added via 'rdma link add rxe0 type rxe netdev eth0'.
networkThe attacker must be able to send UDP packets to port 4791 on the target host.
authNo authentication, QP creation, or connection setup is required.

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