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 <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Reviewed-by: Suman Ghosh <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

0 files changed, 0 insertions, 0 deletions