This is a note to let you know that I've just added the patch titled
ipv6: prevent possible UAF in ip6_xmit()
to the 6.1-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-prevent-possible-uaf-in-ip6_xmit.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0ad605bd732f80427d1d7c4101328c96d4cc6545
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Tue Aug 20 16:08:59 2024 +0000
ipv6: prevent possible UAF in ip6_xmit()
[ Upstream commit 2d5ff7e339d04622d8282661df36151906d0e1c7 ]
If skb_expand_head() returns NULL, skb has been freed
and the associated dst/idev could also have been freed.
We must use rcu_read_lock() to prevent a possible UAF.
Fixes: 0c9f227bee11 ("ipv6: use skb_expand_head in ip6_xmit")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Vasily Averin <vasily.averin@xxxxxxxxx>
Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
Link: https://patch.msgid.link/20240820160859.3786976-4-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 cfca9627398ee..f2227e662d1cf 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -278,11 +278,15 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
head_room += opt->opt_nflen + opt->opt_flen;
if (unlikely(head_room > skb_headroom(skb))) {
+ /* Make sure idev stays alive */
+ rcu_read_lock();
skb = skb_expand_head(skb, head_room);
if (!skb) {
IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
+ rcu_read_unlock();
return -ENOBUFS;
}
+ rcu_read_unlock();
}
if (opt) {
