netfilter: nft_counter: fix reset of counters on 32bit archs

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[ Upstream commit 1e13f27e06 ]

nft_counter_reset() calls u64_stats_add() with a negative value to reset
the counter. This will work on 64bit archs, hence the negative value
added will wrap as a 64bit value which then can wrap the stat counter as
well.

On 32bit archs, the added negative value will wrap as a 32bit value and
_not_ wrapping the stat counter properly. In most cases, this would just
lead to a very large 32bit value being added to the stat counter.

Fix by introducing u64_stats_sub().

Fixes: 4a1d3acd6e ("netfilter: nft_counter: Use u64_stats_t for statistic.")
Signed-off-by: Anders Grahn <anders.grahn@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

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Anders Grahn 2026-02-03 14:48:30 +01:00 • committed by Sasha Levin

parent bce4581e02

commit 4f899976ee

2 changed files with 12 additions and 2 deletions

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10

include/linux/u64_stats_sync.h

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4

net/netfilter/nft_counter.c

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