From: Oliver Neukum <oneukum@suse.com>
To: syzbot <syzbot+0c90fc937c84f97d0aa6@syzkaller.appspotmail.com>,
keescook@chromium.org, andreyknvl@google.com,
syzkaller-bugs@googlegroups.com, mchehab@kernel.org,
tglx@linutronix.de, sakari.ailus@linux.intel.com,
kstewart@linuxfoundation.org, allison@lohutok.net,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
linux-usb@vger.kernel.org, hverkuil-cisco@xs4all.nl
Subject: Re: KASAN: use-after-free Read in cpia2_usb_disconnect
Date: Wed, 03 Jul 2019 09:42:09 +0200 [thread overview]
Message-ID: <1562139729.5819.28.camel@suse.com> (raw)
In-Reply-To: <0000000000006d7e14058cbc6545@google.com>
Am Dienstag, den 02.07.2019, 18:01 -0700 schrieb syzbot:
> syzbot has found a reproducer for the following crash on:
>
> HEAD commit: 7829a896 usb-fuzzer: main usb gadget fuzzer driver
> git tree: https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=11e19043a00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=f6d4561982f71f63
> dashboard link: https://syzkaller.appspot.com/bug?extid=0c90fc937c84f97d0aa6
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=147d42eda00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=104c268ba00000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+0c90fc937c84f97d0aa6@syzkaller.appspotmail.com
>
> cpia2: Message: count = 1, register[0] = 0x0
> cpia2: Unexpected error: -19
> ==================================================================
> BUG: KASAN: use-after-free in cpia2_usb_disconnect+0x1a4/0x1c0
> drivers/media/usb/cpia2/cpia2_usb.c:898
> Read of size 8 at addr ffff8881cf6c4e50 by task kworker/1:1/22
Please try this:
From a0a73298fc23acb95e7b6487e960be707563eb34 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.com>
Date: Wed, 8 May 2019 12:36:40 +0200
Subject: [PATCH] cpia2_usb: first wake up, then free in disconnect
Kasan reported a use after free in cpia2_usb_disconnect()
It first freed everything and then woke up those waiting.
The reverse order is correct.
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by: syzbot+0c90fc937c84f97d0aa6@syzkaller.appspotmail.com
Fixes: 6c493f8b28c67 ("[media] cpia2: major overhaul to get it in a working state again")
---
drivers/media/usb/cpia2/cpia2_usb.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/media/usb/cpia2/cpia2_usb.c b/drivers/media/usb/cpia2/cpia2_usb.c
index e5d8dee38fe4..44bd7e5ad3eb 100644
--- a/drivers/media/usb/cpia2/cpia2_usb.c
+++ b/drivers/media/usb/cpia2/cpia2_usb.c
@@ -902,7 +902,6 @@ static void cpia2_usb_disconnect(struct usb_interface *intf)
cpia2_unregister_camera(cam);
v4l2_device_disconnect(&cam->v4l2_dev);
mutex_unlock(&cam->v4l2_lock);
- v4l2_device_put(&cam->v4l2_dev);
if(cam->buffers) {
DBG("Wakeup waiting processes\n");
@@ -911,6 +910,8 @@ static void cpia2_usb_disconnect(struct usb_interface *intf)
wake_up_interruptible(&cam->wq_stream);
}
+ v4l2_device_put(&cam->v4l2_dev);
+
LOG("CPiA2 camera disconnected.\n");
}
--
2.16.4
next prev parent reply other threads:[~2019-07-03 7:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-16 11:16 KASAN: use-after-free Read in cpia2_usb_disconnect syzbot
2019-07-03 1:01 ` syzbot
2019-07-03 7:42 ` Oliver Neukum [this message]
2019-07-03 17:10 ` Eric Biggers
2019-07-04 9:36 ` Oliver Neukum
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