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Fencer Vulns
high 7.8

CVE-2022-49840 json

bpf, test_run: Fix alignment problem in bpf_prog_test_run_skb()

published 2025-05-01 18 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-12940

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 4.14.300, 4.19.267, 5.4.225, 5.10.156, 5.15.80, 6.0.10, 6.1
  • linux Debian 14, Debian 13, Debian 12 6.0.10-1

debian advisories DEBIAN-CVE-2022-49840

  • linux Ubuntu 18.04 LTS 4.15.0-206.217
  • linux Ubuntu 20.04 LTS 5.4.0-144.161
  • linux Ubuntu 22.04 LTS 5.15.0-67.74
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1151.164
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1097.105
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1031.35
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1101.110
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1030.37

ubuntu advisories UBUNTU-CVE-2022-49840

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-syms SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 4.12.14-122.261.1
  • kernel-source SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 4.12.14-122.261.1
  • kernel-default SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS, SLE Live Patching 12 SP5 4.12.14-122.261.1
  • kgraft-patch-SLE12-SP5_Update_69 SLE Live Patching 12 SP5 1-8.3.1

suse advisories SUSE-SU-2025:01983-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2022-49840 updated cvss 4.7

kernel: bpf, test_run: Fix alignment problem in bpf_prog_test_run_skb()

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
13 mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.