netdev - [PATCH] tls: fix WARNING in __sk_msg

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Date: Tue,  9 Jan 2024 17:32:35 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+f2977222e0e95cec15c8@...kaller.appspotmail.com
Cc: andrii@...nel.org,
	ast@...nel.org,
	borisp@...dia.com,
	bpf@...r.kernel.org,
	daniel@...earbox.net,
	davem@...emloft.net,
	dhowells@...hat.com,
	edumazet@...gle.com,
	jakub@...udflare.com,
	john.fastabend@...il.com,
	kuba@...nel.org,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org,
	pabeni@...hat.com,
	syzkaller-bugs@...glegroups.com
Subject: [PATCH] tls: fix WARNING in __sk_msg_free

Syzbot constructed 32 scatterlists, and the data members in struct sk_msg_sg 
can only store a maximum of MAX_MSG_FRAGS scatterlists.
However, the value of MAX_MSG_FRAGS=CONFIG_MAX_SKB_FRAG is less than 32, which
leads to the warning reported here.

Prevent similar issues from occurring by checking whether sg.end is greater 
than MAX_MSG_FRAGS.

Reported-and-tested-by: syzbot+f2977222e0e95cec15c8@...kaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@...com>
---
 net/tls/tls_sw.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index e37b4d2e2acd..68dbe821f61d 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -1016,6 +1016,8 @@ static int tls_sw_sendmsg_locked(struct sock *sk, struct msghdr *msg,
 
 		msg_pl = &rec->msg_plaintext;
 		msg_en = &rec->msg_encrypted;
+		if (msg_pl->sg.end >= MAX_MSG_FRAGS)
+			return -EINVAL;
 
 		orig_size = msg_pl->sg.size;
 		full_record = false;
-- 
2.43.0