4.19-stable review patch. If anyone has any objections, please let me know.
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From: Shigeru Yoshida syoshida@redhat.com
[ 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@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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/ip_gre.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index e16373640f4c2..38c8db78cda19 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -683,15 +683,18 @@ 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 &&