net: ipv4: Fix the warning for dereference
authorYajun Deng <yajun.deng@linux.dev>
Mon, 30 Aug 2021 09:16:40 +0000 (17:16 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 1 Feb 2022 16:25:46 +0000 (17:25 +0100)
[ Upstream commit 1b9fbe813016b08e08b22ddba4ddbf9cb1b04b00 ]

Add a if statements to avoid the warning.

Dan Carpenter report:
The patch faf482ca196a: "net: ipv4: Move ip_options_fragment() out of
loop" from Aug 23, 2021, leads to the following Smatch complaint:

    net/ipv4/ip_output.c:833 ip_do_fragment()
    warn: variable dereferenced before check 'iter.frag' (see line 828)

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: faf482ca196a ("net: ipv4: Move ip_options_fragment() out of loop")
Link: https://lore.kernel.org/netdev/20210830073802.GR7722@kadam/T/#t
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net/ipv4/ip_output.c

index fb91a466b2d3467c576fa4775d914b95fbb1aff0..e77afaecc9818e344ab224207ce5dda01c73a413 100644 (file)
@@ -833,7 +833,9 @@ int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 
                /* Everything is OK. Generate! */
                ip_fraglist_init(skb, iph, hlen, &iter);
-               ip_options_fragment(iter.frag);
+
+               if (iter.frag)
+                       ip_options_fragment(iter.frag);
 
                for (;;) {
                        /* Prepare header of the next frame,