This is a note to let you know that I've just added the patch titled
bpf: Fix mismatched RCU unlock flavour in bpf_out_neigh_v6
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-fix-mismatched-rcu-unlock-flavour-in-bpf_out_nei.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ab3bbb39c05e00dd2ba548e5bb14acbb316288e6
Author: Jiawei Ye <jiawei.ye@xxxxxxxxxxx>
Date: Fri Nov 8 08:18:52 2024 +0000
bpf: Fix mismatched RCU unlock flavour in bpf_out_neigh_v6
[ Upstream commit fb86c42a2a5d44e849ddfbc98b8d2f4f40d36ee3 ]
In the bpf_out_neigh_v6 function, rcu_read_lock() is used to begin an RCU
read-side critical section. However, when unlocking, one branch
incorrectly uses a different RCU unlock flavour rcu_read_unlock_bh()
instead of rcu_read_unlock(). This mismatch in RCU locking flavours can
lead to unexpected behavior and potential concurrency issues.
This possible bug was identified using a static analysis tool developed
by myself, specifically designed to detect RCU-related issues.
This patch corrects the mismatched unlock flavour by replacing the
incorrect rcu_read_unlock_bh() with the appropriate rcu_read_unlock(),
ensuring that the RCU critical section is properly exited. This change
prevents potential synchronization issues and aligns with proper RCU
usage patterns.
Fixes: 09eed1192cec ("neighbour: switch to standard rcu, instead of rcu_bh")
Signed-off-by: Jiawei Ye <jiawei.ye@xxxxxxxxxxx>
Acked-by: Yonghong Song <yonghong.song@xxxxxxxxx>
Link: https://lore.kernel.org/r/tencent_CFD3D1C3D68B45EA9F52D8EC76D2C4134306@xxxxxx
Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/core/filter.c b/net/core/filter.c
index b2b551401bc29..fe5ac8da5022f 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2248,7 +2248,7 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb,
rcu_read_unlock();
return ret;
}
- rcu_read_unlock_bh();
+ rcu_read_unlock();
if (dst)
IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
out_drop:
