6.1-stable review patch. If anyone has any objections, please let me know.
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From: Sebastian Andrzej Siewior bigeasy@linutronix.de
[ Upstream commit 1eacdd71b3436b54d5fc8218c4bb0187d92a6892 ]
The sequence counter nft_counter_seq is a per-CPU counter. There is no lock associated with it. nft_counter_do_eval() is using the same counter and disables BH which suggest that it can be invoked from a softirq. This in turn means that nft_counter_offload_stats(), which disables only preemption, can be interrupted by nft_counter_do_eval() leading to two writer for one seqcount_t. This can lead to loosing stats or reading statistics while they are updated.
Disable BH during stats update in nft_counter_offload_stats() to ensure one writer at a time.
Fixes: b72920f6e4a9d ("netfilter: nftables: counter hardware offload support") Signed-off-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Reviewed-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/netfilter/nft_counter.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/netfilter/nft_counter.c b/net/netfilter/nft_counter.c index b5fe7fe4b60db..73e4d278d6c13 100644 --- a/net/netfilter/nft_counter.c +++ b/net/netfilter/nft_counter.c @@ -264,7 +264,7 @@ static void nft_counter_offload_stats(struct nft_expr *expr, struct nft_counter *this_cpu; seqcount_t *myseq;
- preempt_disable(); + local_bh_disable(); this_cpu = this_cpu_ptr(priv->counter); myseq = this_cpu_ptr(&nft_counter_seq);
@@ -272,7 +272,7 @@ static void nft_counter_offload_stats(struct nft_expr *expr, this_cpu->packets += stats->pkts; this_cpu->bytes += stats->bytes; write_seqcount_end(myseq); - preempt_enable(); + local_bh_enable(); }
void nft_counter_init_seqcount(void)