Zihan Xi 63853eb20b netfilter: nf_conntrack: defer invalid log until after unlock
commit 2d19b95c97 upstream.

TCP and SCTP conntrack paths can emit invalid-packet logs while ct->lock
is still held.

When invalid logging is routed to nfnetlink_log and conntrack export is
enabled, the log path can re-enter conntrack netlink glue and dump the
same conntrack again. Protocol attribute dumping may take ct->lock, so
logging while holding that lock can deadlock.

Defer the TCP invalid logs by storing only the minimal log context while
ct->lock is held and emitting the log after unlocking. Also make the TCP
timeout-lowering invalid path return whether a log is needed, then emit
that log after unlocking.

Do the same for the SCTP invalid state-transition log that can be reached
while ct->lock is held.

Add a lockdep assertion to nf_ct_l4proto_log_invalid() so future callers
that log invalid conntracks while holding ct->lock are caught outside TCP
and SCTP as well.

Fixes: 628d694344 ("netfilter: conntrack: reduce timeout when receiving out-of-window fin or rst")
Fixes: d9a6f0d0df ("netfilter: conntrack: prepare tcp_in_window for ternary return value")
Fixes: f71cb8f45d ("netfilter: conntrack: sctp: use nf log infrastructure for invalid packets")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Assisted-by: Codex:gpt-5.4
Signed-off-by: Zihan Xi <zihanx@nebusec.ai>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-08-19 18:13:12 +02:00
2026-08-19 18:13:10 +02:00
2026-05-23 13:03:09 +02:00
2026-08-03 11:15:40 +02:00
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2026-05-23 13:03:09 +02:00
2026-08-09 20:22:05 +02:00
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Linux kernel
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In order to build the documentation, use ``make htmldocs`` or
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    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
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