CVE intelligence and bounded remediation

CVE-2024-44946 — In the Linux kernel, the following vulnerability has been resolved: kcm: Serialise kcm_sendmsg() for the same socket

Medium CVSS 5.5

In the Linux kernel, the following vulnerability has been resolved: kcm: Serialise kcm_sendmsg() for the same socket. syzkaller reported UAF in kcm_release(). [0] The scenario is 1. Thread A builds a skb with MSG_MORE and sets kcm->seq_skb. 2. Thread A resumes building skb from kcm->seq_skb but is blocked by sk_stream_wait_memory() 3. Thread B calls sendmsg() concurrently, finishes building kcm->seq_skb and puts the skb to the write queue 4. Thread A faces an error and finally frees skb that is already in the write queue 5. kcm_release() does double-free the skb in the write queue When a thread is building a MSG_MORE skb, another thread must not touch it. Let's add a per-sk mutex and serialise kcm_sendmsg(). [0]: BUG: KASAN: slab-use-after-free in __skb_unlink include/linux/skbuff.h:2366 [inline] BUG: KASAN: slab-use-after-free in __skb_dequeue include/linux/skbuff.h:2385 [inline] BUG: KASAN: slab-use-after-free in __skb_queue_purge_reason include/linux/skbuff.h:3175 [inline] BUG: KASAN: slab-use-after-free in __skb_queue_purge include/linux/skbuff.h:3181 [inline] BUG: KASAN: slab-use-after-free in kcm_release+0x170/0x4c8 net/kcm/kcmsock.c:1691 Read of size 8 at addr ffff0000ced0f…

Severity
Medium
CVSS
5.5 (3.1)
Published
2024-08-31
CISA KEV
Not currently listed
Ecosystem
linux/kernel
Weaknesses
CWE-416

Affected products

  • linux / linux_kernel
  • linux / linux_kernel / 6.11

Showing 2 representative product identities from 7 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Use-after-free, double free, and expired resource use

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Trace ownership, references, callbacks, asynchronous tasks, and teardown paths around the affected object or resource.
  • Identify reachable inputs and timing or state transitions that can release the object while references remain.
  • Confirm affected builds, allocators, feature flags, architectures, and process privileges.

Remediate safely

  • Apply the maintained ownership or lifetime fix and rebuild all artifacts containing the affected native code.
  • Use explicit ownership, safe reference management, cancellation and join semantics, and idempotent teardown.
  • Add deterministic lifetime tests plus isolated sanitizer and concurrency coverage for shutdown and error paths.

Authoritative sources

Complete CVE record and remediation plan

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