This is a note to let you know that I've just added the patch titled
ipv4: ip_gre: Avoid skb_pull() failure in ipgre_xmit()
to the 5.4-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:
ipv4-ip_gre-avoid-skb_pull-failure-in-ipgre_xmit.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3eb8cb022ac5e64bf5a872ede5079c0b753f355f
Author: Shigeru Yoshida <syoshida@xxxxxxxxxx>
Date: Sun Dec 3 01:14:41 2023 +0900
ipv4: ip_gre: Avoid skb_pull() failure in ipgre_xmit()
[ Upstream commit 80d875cfc9d3711a029f234ef7d680db79e8fa4b ]
In ipgre_xmit(), skb_pull() may fail even if pskb_inet_may_pull() returns
true. For example, applications can use PF_PACKET to create a malformed
packet with no IP header. This type of packet causes a problem such as
uninit-value access.
This patch ensures that skb_pull() can pull the required size by checking
the skb with pskb_network_may_pull() before skb_pull().
Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.")
Signed-off-by: Shigeru Yoshida <syoshida@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Suman Ghosh <sumang@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20231202161441.221135-1-syoshida@xxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index f8f008344273e..db48dec61f305 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -607,15 +607,18 @@ static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
}
if (dev->header_ops) {
+ int pull_len = tunnel->hlen + sizeof(struct iphdr);
+
if (skb_cow_head(skb, 0))
goto free_skb;
tnl_params = (const struct iphdr *)skb->data;
- /* Pull skb since ip_tunnel_xmit() needs skb->data pointing
- * to gre header.
- */
- skb_pull(skb, tunnel->hlen + sizeof(struct iphdr));
+ if (!pskb_network_may_pull(skb, pull_len))
+ goto free_skb;
+
+ /* ip_tunnel_xmit() needs skb->data pointing to gre header. */
+ skb_pull(skb, pull_len);
skb_reset_mac_header(skb);
if (skb->ip_summed == CHECKSUM_PARTIAL &&
