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Message-ID: <20210827084915.GA8737@kili>
Date: Fri, 27 Aug 2021 11:49:15 +0300
From: Dan Carpenter <dan.carpenter@...cle.com>
To: yajun.deng@...ux.dev
Cc: netdev@...r.kernel.org
Subject: [bug report] net: ipv4: Move ip_options_fragment() out of loop
Hello Yajun Deng,
This is a semi-automatic email about new static checker warnings.
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)
net/ipv4/ip_output.c
827 ip_fraglist_init(skb, iph, hlen, &iter);
^^^^^
iter.frag is set here.
828 ip_options_fragment(iter.frag);
^^^^^^^^^
The patch introduces a new dereference here
829
830 for (;;) {
831 /* Prepare header of the next frame,
832 * before previous one went down. */
833 if (iter.frag) {
^^^^^^^^^
But the old code assumed that "iter.frag" could be NULL.
834 IPCB(iter.frag)->flags = IPCB(skb)->flags;
835 ip_fraglist_prepare(skb, &iter);
regards,
dan carpenter
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