linux/net/ipv4/tcp_timer.c
Altan Hacigumus 2b9f6f7065 tcp: make probe0 timer handle expired user timeout
tcp_clamp_probe0_to_user_timeout() computes remaining time in jiffies
using subtraction with an unsigned lvalue.  If elapsed probing time
exceeds the configured TCP_USER_TIMEOUT, the underflow yields a large
value.

This ends up re-arming the probe timer for a full backoff interval
instead of expiring immediately, delaying connection teardown beyond
the configured timeout.

Fix this by preventing underflow so user-set timeout expiration is
handled correctly without extending the probe timer.

Fixes: 344db93ae3 ("tcp: make TCP_USER_TIMEOUT accurate for zero window probes")
Link: https://lore.kernel.org/r/20260414013634.43997-1-ahacigu.linux@gmail.com
Signed-off-by: Altan Hacigumus <ahacigu.linux@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260424014639.54110-1-ahacigu.linux@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-27 19:16:07 -07:00

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26 KiB