CVE-2022-48819: tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-16 · updated 2026-06-17

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.

Affected products

Linux kernel: from 5.16 before 5.16.10; 5.17-rc1, 5.17-rc2, 5.17-rc3 — fixed in 5.16.10

How to fix

Upgrade to a fixed version: Linux kernel 5.16.10. Check the vendor advisory for mitigations.

References

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