In the Linux kernel, the following vulnerability has been resolved:
net: skb: fix cross-cache free of KFENCE-allocated skb head
SKB_SMALL_HEAD_CACHE_SIZE is intentionally set to a non-power-of-2
value (e.g. 704 on x86_64) to avoid collisions with generic kmalloc
bucket sizes. This ensures that skb_kfree_head() can reliably use
skb_end_offset to distinguish skb heads allocated from
skb_small_head_cache vs. generic kmalloc caches.
However, when KFENCE is enabled, kfence_ksize() returns the exact
requested allocation size instead of the slab bucket size. If a caller
(e.g. bpf_test_init) allocates skb head data via kzalloc() and the
requested size happens to equal SKB_SMALL_HEAD_CACHE_SIZE, then
slab_build_skb() -> ksize() returns that exact value. After subtracting
skb_shared_info overhead, skb_end_offset ends up matching
SKB_SMALL_HEAD_HEADROOM, causing skb_kfree_head() to incorrectly free
the object to skb_small_head_cache instead of back to the original
kmalloc cache, resulting in a slab cross-cache free:
kmem_cache_free(skbuff_small_head): Wrong slab cache. Expected
skbuff_small_head but got kmalloc-1k
Fix this by always calling kfree(head) in skb_kfree_head(). This keeps
the free path generic and avoids allocator-specific misclassification
for KFENCE objects.
References
Configurations
Configuration 1 (hide)
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History
20 May 2026, 19:23
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/0f42e3f4fe2a58394e37241d02d9ca6ab7b7d516 - Patch | |
| References | () https://git.kernel.org/stable/c/128b03ccb2582a643983a48a37fda58df80edbde - Patch | |
| References | () https://git.kernel.org/stable/c/2d64618ea846d8d033477311f805ca487d6a6696 - Patch | |
| References | () https://git.kernel.org/stable/c/474e00b935db250cac320d10c1d3cf4e44b46721 - Patch | |
| References | () https://git.kernel.org/stable/c/60313768a8edc7094435975587c00c2d7b834083 - Patch | |
| CPE | cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:* |
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| CWE | CWE-401 | |
| First Time |
Linux linux Kernel
Linux |
|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 5.5 |
27 Apr 2026, 14:16
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
20 Apr 2026, 10:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-04-20 10:16
Updated : 2026-05-20 19:23
NVD link : CVE-2026-31429
Mitre link : CVE-2026-31429
CVE.ORG link : CVE-2026-31429
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-401
Missing Release of Memory after Effective Lifetime