mptcp: pm: add WARN_ON_ONCE guards on extra_subflows underflow

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extra_subflows is a u8 counter that can underflow if a decrement races
with or precedes an increment. While the recently fixed userspace PM
subflow creation path eliminated the primary cause, add defensive
WARN_ON_ONCE guards at both decrement sites to catch any remaining edge
cases rather than silently wrapping to 255.

Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260812-net-next-mptcp-misc-feat-7-3-v1-1-1905a818f6cb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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Tao Cui 2026-08-12 16:55:36 +02:00 • committed by Jakub Kicinski

parent ff31c9a708

commit e99c1ca890

2 changed files with 4 additions and 2 deletions

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3

net/mptcp/pm.c

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3

net/mptcp/protocol.h

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