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Date:   Wed, 4 Aug 2021 04:58:39 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Pavel Skripkin <paskripkin@gmail.com>
Cc:     petkan@nucleusys.com, davem@davemloft.net,
        linux-usb@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        syzbot+02c9f70f3afae308464a@syzkaller.appspotmail.com
Subject: Re: [PATCH] net: pegasus: fix uninit-value in
 get_interrupt_interval
Message-ID: <20210804045839.101fe0f0@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
In-Reply-To: <9576d0cc-1f3e-4acc-4009-79fb2dbeda34@gmail.com>
References: <20210730214411.1973-1-paskripkin@gmail.com>
        <9576d0cc-1f3e-4acc-4009-79fb2dbeda34@gmail.com>
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On Wed, 4 Aug 2021 13:44:05 +0300 Pavel Skripkin wrote:
> On 7/31/21 12:44 AM, Pavel Skripkin wrote:
> > Syzbot reported uninit value pegasus_probe(). The problem was in missing
> > error handling.
> > 
> > get_interrupt_interval() internally calls read_eprom_word() which can
> > fail in some cases. For example: failed to receive usb control message.
> > These cases should be handled to prevent uninit value bug, since
> > read_eprom_word() will not initialize passed stack variable in case of
> > internal failure.
> > 
> > Fail log:
> > 
> > BUG: KMSAN: uninit-value in get_interrupt_interval drivers/net/usb/pegasus.c:746 [inline]
> > BUG: KMSAN: uninit-value in pegasus_probe+0x10e7/0x4080 drivers/net/usb/pegasus.c:1152
> > CPU: 1 PID: 825 Comm: kworker/1:1 Not tainted 5.12.0-rc6-syzkaller #0
> > ...
> > Workqueue: usb_hub_wq hub_event
> > Call Trace:
> >   __dump_stack lib/dump_stack.c:79 [inline]
> >   dump_stack+0x24c/0x2e0 lib/dump_stack.c:120
> >   kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:118
> >   __msan_warning+0x5c/0xa0 mm/kmsan/kmsan_instr.c:197
> >   get_interrupt_interval drivers/net/usb/pegasus.c:746 [inline]
> >   pegasus_probe+0x10e7/0x4080 drivers/net/usb/pegasus.c:1152
> > ....
> > 
> > Local variable ----data.i@pegasus_probe created at:
> >   get_interrupt_interval drivers/net/usb/pegasus.c:1151 [inline]
> >   pegasus_probe+0xe57/0x4080 drivers/net/usb/pegasus.c:1152
> >   get_interrupt_interval drivers/net/usb/pegasus.c:1151 [inline]
> >   pegasus_probe+0xe57/0x4080 drivers/net/usb/pegasus.c:1152
> > 
> > Reported-and-tested-by: syzbot+02c9f70f3afae308464a@syzkaller.appspotmail.com
> > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
> 
> Hi, David and Jakub!
> 
> Should I rebase this patch on top of Petko's clean-up patches? :
> 
> 1. https://git.kernel.org/netdev/net/c/8a160e2e9aeb
> 2. https://git.kernel.org/netdev/net/c/bc65bacf239d

Yes, rebase on top of net, the patches are there. Please mark the new
submission as [PATCH net v2].