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Medium severity5.5NVD Advisory· Published Aug 17, 2024· Updated May 12, 2026

CVE-2024-42272

CVE-2024-42272

Description

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

sched: act_ct: take care of padding in struct zones_ht_key

Blamed commit increased lookup key size from 2 bytes to 16 bytes, because zones_ht_key got a struct net pointer.

Make sure rhashtable_lookup() is not using the padding bytes which are not initialized.

BUG: KMSAN: uninit-value in rht_ptr_rcu include/linux/rhashtable.h:376 [inline] BUG: KMSAN: uninit-value in __rhashtable_lookup include/linux/rhashtable.h:607 [inline] BUG: KMSAN: uninit-value in rhashtable_lookup include/linux/rhashtable.h:646 [inline] BUG: KMSAN: uninit-value in rhashtable_lookup_fast include/linux/rhashtable.h:672 [inline] BUG: KMSAN: uninit-value in tcf_ct_flow_table_get+0x611/0x2260 net/sched/act_ct.c:329 rht_ptr_rcu include/linux/rhashtable.h:376 [inline] __rhashtable_lookup include/linux/rhashtable.h:607 [inline] rhashtable_lookup include/linux/rhashtable.h:646 [inline] rhashtable_lookup_fast include/linux/rhashtable.h:672 [inline] tcf_ct_flow_table_get+0x611/0x2260 net/sched/act_ct.c:329 tcf_ct_init+0xa67/0x2890 net/sched/act_ct.c:1408 tcf_action_init_1+0x6cc/0xb30 net/sched/act_api.c:1425 tcf_action_init+0x458/0xf00 net/sched/act_api.c:1488 tcf_action_add net/sched/act_api.c:2061 [inline] tc_ctl_action+0x4be/0x19d0 net/sched/act_api.c:2118 rtnetlink_rcv_msg+0x12fc/0x1410 net/core/rtnetlink.c:6647 netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2550 rtnetlink_rcv+0x34/0x40 net/core/rtnetlink.c:6665 netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline] netlink_unicast+0xf52/0x1260 net/netlink/af_netlink.c:1357 netlink_sendmsg+0x10da/0x11e0 net/netlink/af_netlink.c:1901 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:745 ____sys_sendmsg+0x877/0xb60 net/socket.c:2597 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2651 __sys_sendmsg net/socket.c:2680 [inline] __do_sys_sendmsg net/socket.c:2689 [inline] __se_sys_sendmsg net/socket.c:2687 [inline] __x64_sys_sendmsg+0x307/0x4a0 net/socket.c:2687 x64_sys_call+0x2dd6/0x3c10 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable key created at: tcf_ct_flow_table_get+0x4a/0x2260 net/sched/act_ct.c:324 tcf_ct_init+0xa67/0x2890 net/sched/act_ct.c:1408

AI Insight

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

A use of uninitialized memory in Linux kernel's act_ct network filter due to uninitialized padding in zones_ht_key structure, leading to KMSAN warning and potential information disclosure.

Vulnerability

The sched: act_ct subsystem in the Linux kernel had a use of uninitialized memory vulnerability, identified as CVE-2024-42272. The root cause is that the zones_ht_key structure was enlarged to 16 bytes (from 2 bytes) to include a struct net pointer, but the padding bytes introduced by this change were not explicitly initialized before using the structure as a key in a rhashtable lookup. This leads to rhashtable_lookup() reading uninitialized padding data, triggering a KMSAN uninit-value bug, as shown in the kernel bug trace [1].

Exploitation

The vulnerability can be triggered by a local attacker with the ability to configure network actions (tc actions), specifically by initializing a conntrack action via tcf_ct_init(). The attack surface requires local access and the capability to add tc filters, which typically requires root or CAP_NET_ADMIN privileges. The uninitialized memory is read during the rhashtable lookup in tcf_ct_flow_table_get(), which is called during the initialization of the action [1].

Impact

An attacker could potentially read sensitive kernel memory, including pointers or other data, through the uninitialized padding bytes. While the primary reported symptom is a kernel bug warning (KMSAN), it could theoretically lead to information disclosure if the uninitialized data is used in further processing or exposed to user space. The CVSS v3 score is 5.5 (Medium), reflecting the need for local access and the potential for information disclosure.

Mitigation

The vulnerability has been patched in the Linux kernel by fixing the initialization of the zones_ht_key structure to ensure all padding bytes are cleared before use. The fix is available in multiple stable kernel commits [2][3][4]. Users should update their kernel to a version containing the fix. Siemens has also listed this CVE as affecting the SIMATIC S7-1500 TM MFP - GNU/Linux subsystem, recommending users apply the vendor-provided kernel updates [1].

References
  1. SSA-265688
  2. Making sure you're not a bot!
  3. Making sure you're not a bot!
  4. Making sure you're not a bot!

AI Insight generated on May 20, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected products

63

Patches

0

No patches discovered yet.

Vulnerability mechanics

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References

9

News mentions

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