[net,1/1] netfilter: nft_set_pipapo_avx2: disable softinterrupts

Commit Message

Pablo Neira Ayuso July 24, 2024, 8:13 a.m. UTC

From: Florian Westphal <[e-mail]>

We need to disable softinterrupts, else we get following problem:

1. pipapo_avx2 called from process context; fpu usable
2. preempt_disable() called, pcpu scratchmap in use
3. softirq handles rx or tx, we re-enter pipapo_avx2
4. fpu busy, fallback to generic non-avx version
5. fallback reuses scratch map and index, which are in use
   by the preempted process

Handle this same way as generic version by first disabling
softinterrupts while the scratchmap is in use.

Fixes: f0b3d338064e ("netfilter: nft_set_pipapo_avx2: Add irq_fpu_usable() check, fallback to non-AVX2 version")
Cc: Stefano Brivio <[e-mail]>
Signed-off-by: Florian Westphal <[e-mail]>
Reviewed-by: Stefano Brivio <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>
---
 net/netfilter/nft_set_pipapo_avx2.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

Comments

[e-mail] July 25, 2024, 9:30 a.m. UTC | #1

Hello:

This patch was applied to netdev/net.git (main)
by Pablo Neira Ayuso <[e-mail]>:

On Wed, 24 Jul 2024 10:13:05 +0200 you wrote:
> From: Florian Westphal <[e-mail]>
> 
> We need to disable softinterrupts, else we get following problem:
> 
> 1. pipapo_avx2 called from process context; fpu usable
> 2. preempt_disable() called, pcpu scratchmap in use
> 3. softirq handles rx or tx, we re-enter pipapo_avx2
> 4. fpu busy, fallback to generic non-avx version
> 5. fallback reuses scratch map and index, which are in use
>    by the preempted process
> 
> [...]

Here is the summary with links:
  - [net,1/1] netfilter: nft_set_pipapo_avx2: disable softinterrupts
    https://git.kernel.org/netdev/net/c/a16909ae9982

You are awesome, thank you!

Patch

diff --git a/net/netfilter/nft_set_pipapo_avx2.c b/net/netfilter/nft_set_pipapo_avx2.c
index 8910a5ac7ed1..b8d3c3213efe 100644
--- a/net/netfilter/nft_set_pipapo_avx2.c
+++ b/net/netfilter/nft_set_pipapo_avx2.c
@@ -1139,8 +1139,14 @@  bool nft_pipapo_avx2_lookup(const struct net *net, const struct nft_set *set,
 	bool map_index;
 	int i, ret = 0;
 
-	if (unlikely(!irq_fpu_usable()))
-		return nft_pipapo_lookup(net, set, key, ext);
+	local_bh_disable();
+
+	if (unlikely(!irq_fpu_usable())) {
+		bool fallback_res = nft_pipapo_lookup(net, set, key, ext);
+
+		local_bh_enable();
+		return fallback_res;
+	}
 
 	m = rcu_dereference(priv->match);
 
@@ -1155,6 +1161,7 @@  bool nft_pipapo_avx2_lookup(const struct net *net, const struct nft_set *set,
 	scratch = *raw_cpu_ptr(m->scratch);
 	if (unlikely(!scratch)) {
 		kernel_fpu_end();
+		local_bh_enable();
 		return false;
 	}
 
@@ -1235,6 +1242,7 @@  bool nft_pipapo_avx2_lookup(const struct net *net, const struct nft_set *set,
 	if (i % 2)
 		scratch->map_index = !map_index;
 	kernel_fpu_end();
+	local_bh_enable();
 
 	return ret >= 0;
 }