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authorShigeru Yoshida <syoshida@redhat.com>2023-12-03 01:14:41 +0900
committerPaolo Abeni <pabeni@redhat.com>2023-12-06 10:08:05 +0100
commit80d875cfc9d3711a029f234ef7d680db79e8fa4b (patch)
tree97a08fefbda89deee425d59f547b9b063075380a /net/ipv4
parentefd563ff1a7e692408c9d44bec3d90949f7a9557 (diff)
ipv4: ip_gre: Avoid skb_pull() failure in ipgre_xmit()
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@redhat.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Suman Ghosh <sumang@marvell.com> Link: https://lore.kernel.org/r/20231202161441.221135-1-syoshida@redhat.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/ip_gre.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 22a26d1d29a0..5169c3c72cff 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -635,15 +635,18 @@ 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 &&