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tcp: Fix potential UAF in reqsk_timer_handler().

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When TCP socket migration fails at inet_ehash_insert() in
reqsk_timer_handler(), we jump to the no_ownership: label
and free the new reqsk immediately with __reqsk_free().

Thus, we must stop the new reqsk's timer before jumping to the
label, but the timer might be missed since the cited commit,
resulting in UAF.

As we are in the original reqsk's timer context, we can safely
call timer_delete_sync() for the new reqsk.

Let's pass false to __inet_csk_reqsk_queue_drop() to stop
the new reqsk's timer.

Fixes: 83fccfc394 ("inet: fix potential deadlock in reqsk_queue_unlink()")
Reported-by: Damiano Melotti <melotti@google.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260506035954.1563147-2-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima
2026-05-06 03:59:18 +00:00
committed by Jakub Kicinski
parent fcee7d82f2
commit 97c8a3c1f7
1 changed files with 1 additions and 1 deletions
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2
net/ipv4/inet_connection_sock.c
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@@ -1108,7 +1108,7 @@ static void reqsk_timer_handler(struct timer_list *t)
if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
/* delete timer */
__inet_csk_reqsk_queue_drop(sk_listener, nreq, true);
__inet_csk_reqsk_queue_drop(sk_listener, nreq, false);
goto no_ownership;
}