This is a note to let you know that I've just added the patch titled
ipv6: fix possible UAF in ip6_finish_output2()
to the 6.6-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:
ipv6-fix-possible-uaf-in-ip6_finish_output2.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 88c73a47f1685aaaa53289c52b43ff1f0580c078
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Tue Aug 20 16:08:58 2024 +0000
ipv6: fix possible UAF in ip6_finish_output2()
[ Upstream commit da273b377ae0d9bd255281ed3c2adb228321687b ]
If skb_expand_head() returns NULL, skb has been freed
and associated dst/idev could also have been freed.
We need to hold rcu_read_lock() to make sure the dst and
associated idev are alive.
Fixes: 5796015fa968 ("ipv6: allocate enough headroom in ip6_finish_output2()")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Vasily Averin <vasily.averin@xxxxxxxxx>
Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
Link: https://patch.msgid.link/20240820160859.3786976-3-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 8d4aaa4029b3e..9cff86c01abca 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -70,11 +70,15 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
/* Be paranoid, rather than too clever. */
if (unlikely(hh_len > skb_headroom(skb)) && dev->header_ops) {
+ /* Make sure idev stays alive */
+ rcu_read_lock();
skb = skb_expand_head(skb, hh_len);
if (!skb) {
IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
+ rcu_read_unlock();
return -ENOMEM;
}
+ rcu_read_unlock();
}
hdr = ipv6_hdr(skb);
