bpf, test_run: Fix alignment problem in bpf_prog_test_run_skb()

Description

In the Linux kernel, the following vulnerability has been resolved: bpf, test_run: Fix alignment problem in bpf_prog_test_run_skb() We got a syzkaller problem because of aarch64 alignment fault if KFENCE enabled. When the size from user bpf program is an odd number, like 399, 407, etc, it will cause the struct skb_shared_info's unaligned access. As seen below: BUG: KFENCE: use-after-free read in __skb_clone+0x23c/0x2a0 net/core/skbuff.c:1032 Use-after-free read at 0xffff6254fffac077 (in kfence-#213): __lse_atomic_add arch/arm64/include/asm/atomic_lse.h:26 [inline] arch_atomic_add arch/arm64/include/asm/atomic.h:28 [inline] arch_atomic_inc include/linux/atomic-arch-fallback.h:270 [inline] atomic_inc include/asm-generic/atomic-instrumented.h:241 [inline] __skb_clone+0x23c/0x2a0 net/core/skbuff.c:1032 skb_clone+0xf4/0x214 net/core/skbuff.c:1481 ____bpf_clone_redirect net/core/filter.c:2433 [inline] bpf_clone_redirect+0x78/0x1c0 net/core/filter.c:2420 bpf_prog_d3839dd9068ceb51+0x80/0x330 bpf_dispatcher_nop_func include/linux/bpf.h:728 [inline] bpf_test_run+0x3c0/0x6c0 net/bpf/test_run.c:53 bpf_prog_test_run_skb+0x638/0xa7c net/bpf/test_run.c:594 bpf_prog_test_run kernel/bpf/syscall.c:3148 [inline] __do_sys_bpf kernel/bpf/syscall.c:4441 [inline] __se_sys_bpf+0xad0/0x1634 kernel/bpf/syscall.c:4381 kfence-#213: 0xffff6254fffac000-0xffff6254fffac196, size=407, cache=kmalloc-512 allocated by task 15074 on cpu 0 at 1342.585390s: kmalloc include/linux/slab.h:568 [inline] kzalloc include/linux/slab.h:675 [inline] bpf_test_init.isra.0+0xac/0x290 net/bpf/test_run.c:191 bpf_prog_test_run_skb+0x11c/0xa7c net/bpf/test_run.c:512 bpf_prog_test_run kernel/bpf/syscall.c:3148 [inline] __do_sys_bpf kernel/bpf/syscall.c:4441 [inline] __se_sys_bpf+0xad0/0x1634 kernel/bpf/syscall.c:4381 __arm64_sys_bpf+0x50/0x60 kernel/bpf/syscall.c:4381 To fix the problem, we adjust @size so that (@size + @hearoom) is a multiple of SMP_CACHE_BYTES. So we make sure the struct skb_shared_info is aligned to a cache line.

Timeline

Scores

EPSS (exploitation in 30 days)

0.22% · top 87% of all CVEs (7 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.

Weakness

• CWE-416 Use After Free (opens in a new tab)All about CWE-416 and its CVEs

Affected products

• Linux · Linux

  • affected 1cf1cae963c2e6032aebe1637e995bc2f5d330f4 – < 047824a730699c6c66df43306b80f700c9dfc2fd
  • affected 1cf1cae963c2e6032aebe1637e995bc2f5d330f4 – < 730fb1ef974a13915bc7651364d8b3318891cd70
  • affected 1cf1cae963c2e6032aebe1637e995bc2f5d330f4 – < 7a704dbfd3735304e261f2787c52fbc7c3884736
  • affected 1cf1cae963c2e6032aebe1637e995bc2f5d330f4 – < e60f37a1d379c821c17b08f366412dce9ef3d99f
  • affected 1cf1cae963c2e6032aebe1637e995bc2f5d330f4 – < eaa8edd86514afac9deb9bf9a5053e74f37edf40
  • affected 1cf1cae963c2e6032aebe1637e995bc2f5d330f4 – < 1b597f2d6a55e9f549989913860ad5170da04964
  • affected 1cf1cae963c2e6032aebe1637e995bc2f5d330f4 – < d3fd203f36d46aa29600a72d57a1b61af80e4a25

• Linux · Linux

  • affected 4.12
  • unaffected < 4.12
  • unaffected 4.14.300 – ≤ 4.14.*
  • unaffected 4.19.267 – ≤ 4.19.*
  • unaffected 5.4.225 – ≤ 5.4.*
  • unaffected 5.10.156 – ≤ 5.10.*
  • unaffected 5.15.80 – ≤ 5.15.*
  • unaffected 6.0.10 – ≤ 6.0.*
  • unaffected 6.1 – ≤ *

References (7)

• https://git.kernel.org/stable/c/047824a730699c6c66df43306b80f700c9dfc2fd (opens in a new tab)
• https://git.kernel.org/stable/c/730fb1ef974a13915bc7651364d8b3318891cd70 (opens in a new tab)
• https://git.kernel.org/stable/c/7a704dbfd3735304e261f2787c52fbc7c3884736 (opens in a new tab)
• https://git.kernel.org/stable/c/e60f37a1d379c821c17b08f366412dce9ef3d99f (opens in a new tab)
• https://git.kernel.org/stable/c/eaa8edd86514afac9deb9bf9a5053e74f37edf40 (opens in a new tab)
• https://git.kernel.org/stable/c/1b597f2d6a55e9f549989913860ad5170da04964 (opens in a new tab)
• https://git.kernel.org/stable/c/d3fd203f36d46aa29600a72d57a1b61af80e4a25 (opens in a new tab)

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2022-49840](https://trackcve.app/badge/CVE-2022-49840.svg)](https://trackcve.app/cve/CVE-2022-49840)

Record last updated 11 May 2026, 19:07 UTC.