CVE-2022-48819

EPSS 0.03%
Veröffentlicht 16.07.2024 12:15:05
Zuletzt bearbeitet 07.10.2025 19:53:45
Quelle 416baaa9-dc9f-4396-8d5f-8c081f
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tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case

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.