From: Phong Tran <tranmanphong@gmail.com>
To: mchehab@kernel.org, hans.verkuil@cisco.com,
keescook@chromium.org, skhan@linuxfoundation.org
Cc: tranmanphong@gmail.com, linux-media@vger.kernel.org,
linux-kernel-mentees@lists.linuxfoundation.org
Subject: Analyze syzbot report technisat_usb2_rc_query KASAN
Date: Tue, 2 Jul 2019 07:49:26 +0700 [thread overview]
Message-ID: <ede75d50-7475-3478-b30f-ef9077b6bf48@gmail.com> (raw)
Hello,
I did a checking for this report of syzbot [1]
From the call stack of dump log:
There shows that a problem within technisat_usb2_get_ir()
BUG: KASAN: slab-out-of-bounds in technisat_usb2_get_ir
drivers/media/usb/dvb-usb/technisat-usb2.c:664 [inline]
BUG: KASAN: slab-out-of-bounds in technisat_usb2_rc_query+0x5fa/0x660
drivers/media/usb/dvb-usb/technisat-usb2.c:679
Read of size 1 at addr ffff8880a8791ea8 by task kworker/0:1/12
Take a look into while loop in technisat_usb2_get_ir().
I recognized that a problem. The loop will not break out with the
condition doesn't reach. Then "b++" will go wrong and buffer will be
overflow.
while (1) {
[...]
b++;
if (*b == 0xff) {
ev.pulse = 0;
ev.duration = 888888*2;
ir_raw_event_store(d->rc_dev, &ev);
break;
}
}
I would propose changing the loop condition by checking the address of
the buffer. If acceptable, I will send this patch to the mailing-list.
eg:
- while (1) {
+ while (b != (buf + 63)) {
[...]
}
Tested with syzbot, result is good [2].
[1] https://syzkaller.appspot.com/bug?extid=eaaaf38a95427be88f4b
[2] https://groups.google.com/d/msg/syzkaller-bugs/CySBCKuUOOs/0hKq1CdjCwAJ
Phong
next reply other threads:[~2019-07-02 0:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 0:49 Phong Tran [this message]
2019-07-02 4:45 ` [Linux-kernel-mentees] Analyze syzbot report technisat_usb2_rc_query KASAN Greg KH
2019-07-02 14:06 ` Phong Tran
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