[PATCH net-next 4/4] net: tcp: reset skb drop reason to NOT_SPCIFIED in tcp_v4_rcv()

[menglong8 . dong]

From: Menglong Dong <imagedong@xxxxxxxxxxx>

The 'drop_reason' that passed to kfree_skb_reason() in tcp_v4_rcv()
can be SKB_NOT_DROPPED_YET(0), as it is used as the return value of
tcp_inbound_md5_hash().

And it can panic the kernel with NULL pointer in
net_dm_packet_report_size() if the reason is 0, as drop_reasons[0]
is NULL.

Fixes: 1330b6ef3313 ("skb: make drop reason booleanable")

Signed-off-by: Menglong Dong <imagedong@xxxxxxxxxxx>
---
 net/ipv4/tcp_ipv4.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 918816ec5dd4..24eb42497a71 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2101,6 +2101,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
 	}
 
 discard_it:
+	SKB_DR_OR(drop_reason, NOT_SPECIFIED);
 	/* Discard frame. */
 	kfree_skb_reason(skb, drop_reason);
 	return 0;
-- 
2.36.1