From: Menglong Dong <imagedong@tencent.com>
Date: Fri, 13 May 2022 03:03:39 +0000 (+0800)
Subject: net: tcp: reset 'drop_reason' to NOT_SPCIFIED in tcp_v{4,6}_rcv()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=f8319dfd1b3b3be6c08795017fc30f880f8bc861;p=linux.git

net: tcp: reset 'drop_reason' to NOT_SPCIFIED in tcp_v{4,6}_rcv()

The 'drop_reason' that passed to kfree_skb_reason() in tcp_v4_rcv()
and tcp_v6_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")
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 218ad871c0e49..f09bdfc6a3213 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2101,6 +2101,7 @@ bad_packet:
 	}
 
 discard_it:
+	SKB_DR_OR(drop_reason, NOT_SPECIFIED);
 	/* Discard frame. */
 	kfree_skb_reason(skb, drop_reason);
 	return 0;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 60bdec257ba72..636ed23d9af04 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1509,6 +1509,7 @@ reset:
 discard:
 	if (opt_skb)
 		__kfree_skb(opt_skb);
+	SKB_DR_OR(reason, NOT_SPECIFIED);
 	kfree_skb_reason(skb, reason);
 	return 0;
 csum_err: