5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ 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>
---
net/ipv6/ip6_output.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 1d06b71c1adad..8054a4a2f2a5e 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -69,11 +69,15 @@ 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);
--
2.43.0
