Re: [PATCH ipsec 7/7] xfrm: leave the sequence counter unchanged on ESN overflow

2026-09-30, 14:45:24 +0000, Jérémy Jean wrote:

When the 64-bit ESN counter overflows, xfrm_replay_overflow_offload_esn()
rejects the packet and rolls back the stored counter. It decrements
replay_esn->oseq even though only the local oseq has advanced, which
can later induce a reuse of the last sequence number and the
corresponding AES-GCM nonce. Both IPv4 and IPv6 are affected, yet,
processing about 2^64 packets under a single key is required to
trigger this bug, which is highly unlikely in regular use cases.

Leave the stored low word unchanged on overflow. The high word still
needs to be restored because it was already incremented.

nit: using "low word" and "high word" instead of the actual variable
names doesn't help the readability of your commit messages

Fixes: d7dbefc45cf5 ("xfrm: Add xfrm_replay_overflow functions for offloading")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Jérémy Jean <redacted>
---
 net/xfrm/xfrm_replay.c | 1 -
 1 file changed, 1 deletion(-)

I ran into that one as well while I was reviewing your previous
patches, but didn't get around to posting a patch.

Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>

-- 
Sabrina