From: Alan Stern <stern@rowland.harvard.edu>
To: syzbot <syzbot+44e64397bd81d5e84cba@syzkaller.appspotmail.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Hans Verkuil <hverkuil@xs4all.nl>
Cc: linux-usb@vger.kernel.org, linux-media@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: memory leak in hub_event
Date: Mon, 23 Nov 2020 16:53:45 -0500 [thread overview]
Message-ID: <20201123215345.GA721643@rowland.harvard.edu> (raw)
In-Reply-To: <000000000000cc9e3405b4cc4ff8@google.com>
Quick summary: syzbot found a memory leak in the gspca driver,
apparently caused by a reference being taken but not released in a
probe failure pathway.
On Mon, Nov 23, 2020 at 12:48:08PM -0800, syzbot wrote:
> Hello,
>
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> memory leak in usb_set_configuration
>
> BUG: memory leak
> unreferenced object 0xffff8881268a1800 (size 1024):
> comm "kworker/0:2", pid 3644, jiffies 4294944749 (age 12.820s)
> hex dump (first 32 bytes):
> 48 f3 6a 26 81 88 ff ff 48 f3 6a 26 81 88 ff ff H.j&....H.j&....
> 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> backtrace:
> [<0000000089bfe22c>] kmalloc include/linux/slab.h:552 [inline]
> [<0000000089bfe22c>] kzalloc include/linux/slab.h:664 [inline]
> [<0000000089bfe22c>] usb_set_configuration+0x18c/0xb90 drivers/usb/core/message.c:1987
> [<00000000207f81de>] usb_generic_driver_probe+0x8c/0xc0 drivers/usb/core/generic.c:238
> [<000000007aa490e0>] usb_probe_device+0x5c/0x140 drivers/usb/core/driver.c:293
Okay, this does seem to pinpoint the problem. gspca_dev_probe2() calls
v4l2_device_register() at the start, but doesn't call
v4l2_device_disconnect() upon failure.
I'm not at all familiar with the design of the v4l2 subsystem. Mauro or
Hans: Is this the right solution?
Alan Stern
#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 4d02da97
Index: usb-devel/drivers/media/usb/gspca/gspca.c
===================================================================
--- usb-devel.orig/drivers/media/usb/gspca/gspca.c
+++ usb-devel/drivers/media/usb/gspca/gspca.c
@@ -1575,6 +1575,7 @@ out:
input_unregister_device(gspca_dev->input_dev);
#endif
v4l2_ctrl_handler_free(gspca_dev->vdev.ctrl_handler);
+ v4l2_device_disconnect(&gspca_dev->v4l2_dev);
kfree(gspca_dev->usb_buf);
kfree(gspca_dev);
return ret;
next prev parent reply other threads:[~2020-11-23 21:54 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 15:15 memory leak in hub_event syzbot
2020-11-20 16:56 ` Alan Stern
2020-11-20 16:56 ` syzbot
2020-11-20 17:00 ` Alan Stern
2020-11-23 18:29 ` Andrey Konovalov
2020-11-23 18:44 ` syzbot
2020-11-23 19:32 ` Alan Stern
2020-11-23 19:42 ` syzbot
2020-11-23 19:53 ` Alan Stern
2020-11-23 20:01 ` syzbot
2020-11-23 20:38 ` Alan Stern
2020-11-23 20:48 ` syzbot
2020-11-23 21:53 ` Alan Stern [this message]
2020-11-23 22:09 ` syzbot
2020-11-23 22:24 ` Alan Stern
2020-11-24 11:38 ` Hans Verkuil
2020-11-24 16:00 ` [PATCH] media: gspca: Fix memory leak in probe Alan Stern
2020-12-02 8:58 ` Hans Verkuil
2020-12-02 17:20 ` [PATCH v2] " Alan Stern
2020-12-02 16:22 ` memory leak in hub_event Alan Stern
2020-12-02 16:37 ` syzbot
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