linux-stable.git/drivers/media, branch v3.16.83

media: fix media devnode ioctl/syscall and unregister race

2020-04-28T18:03:51+00:00

commit 6f0dd24a084a17f9984dd49dffbf7055bf123993 upstream.

Media devnode open/ioctl could be in progress when media device unregister
is initiated. System calls and ioctls check media device registered status
at the beginning, however, there is a window where unregister could be in
progress without changing the media devnode status to unregistered.

process 1				process 2
fd = open(/dev/media0)
media_devnode_is_registered()
	(returns true here)

					media_device_unregister()
						(unregister is in progress
						and devnode isn't
						unregistered yet)
					...
ioctl(fd, ...)
__media_ioctl()
media_devnode_is_registered()
	(returns true here)
					...
					media_devnode_unregister()
					...
					(driver releases the media device
					memory)

media_device_ioctl()
	(By this point
	devnode->media_dev does not
	point to allocated memory.
	use-after free in in mutex_lock_nested)

BUG: KASAN: use-after-free in mutex_lock_nested+0x79c/0x800 at addr
ffff8801ebe914f0

Fix it by clearing register bit when unregister starts to avoid the race.

process 1                               process 2
fd = open(/dev/media0)
media_devnode_is_registered()
        (could return true here)

                                        media_device_unregister()
                                                (clear the register bit,
						 then start unregister.)
                                        ...
ioctl(fd, ...)
__media_ioctl()
media_devnode_is_registered()
        (return false here, ioctl
	 returns I/O error, and
	 will not access media
	 device memory)
                                        ...
                                        media_devnode_unregister()
                                        ...
                                        (driver releases the media device
					 memory)

Signed-off-by: Shuah Khan 
Suggested-by: Sakari Ailus 
Reported-by: Mauro Carvalho Chehab 
Tested-by: Mauro Carvalho Chehab 
Signed-off-by: Mauro Carvalho Chehab 
[bwh: Backported to 3.16: adjut filename, context]
Signed-off-by: Ben Hutchings

media: fix use-after-free in cdev_put() when app exits after driver unbind

2020-04-28T18:03:50+00:00

commit 5b28dde51d0ccc54cee70756e1800d70bed7114a upstream.

When driver unbinds while media_ioctl is in progress, cdev_put() fails with
when app exits after driver unbinds.

Add devnode struct device kobj as the cdev parent kobject. cdev_add() gets
a reference to it and releases it in cdev_del() ensuring that the devnode
is not deallocated as long as the application has the device file open.

media_devnode_register() initializes the struct device kobj before calling
cdev_add(). media_devnode_unregister() does cdev_del() and then deletes the
device. devnode is released when the last reference to the struct device is
gone.

This problem is found on uvcvideo, em28xx, and au0828 drivers and fix has
been tested on all three.

kernel: [  193.599736] BUG: KASAN: use-after-free in cdev_put+0x4e/0x50
kernel: [  193.599745] Read of size 8 by task media_device_te/1851
kernel: [  193.599792] INFO: Allocated in __media_device_register+0x54
kernel: [  193.599951] INFO: Freed in media_devnode_release+0xa4/0xc0

kernel: [  193.601083] Call Trace:
kernel: [  193.601093]  [] dump_stack+0x67/0x94
kernel: [  193.601102]  [] print_trailer+0x112/0x1a0
kernel: [  193.601111]  [] object_err+0x34/0x40
kernel: [  193.601119]  [] kasan_report_error+0x224/0x530
kernel: [  193.601128]  [] ? kzfree+0x2d/0x40
kernel: [  193.601137]  [] ? kfree+0x1d2/0x1f0
kernel: [  193.601154]  [] ? cdev_put+0x4e/0x50
kernel: [  193.601162]  [] cdev_put+0x4e/0x50
kernel: [  193.601170]  [] __fput+0x52b/0x6c0
kernel: [  193.601179]  [] ? switch_task_namespaces+0x2a
kernel: [  193.601188]  [] ____fput+0xe/0x10
kernel: [  193.601196]  [] task_work_run+0x133/0x1f0
kernel: [  193.601204]  [] ? switch_task_namespaces+0x5e
kernel: [  193.601213]  [] do_exit+0x72c/0x2c20
kernel: [  193.601224]  [] ? release_task+0x1250/0x1250
-
-
-
kernel: [  193.601360]  [] ? exit_to_usermode_loop+0xe7
kernel: [  193.601368]  [] exit_to_usermode_loop+0x120
kernel: [  193.601376]  [] syscall_return_slowpath+0x16a
kernel: [  193.601386]  [] entry_SYSCALL_64_fastpath+0xa6

Signed-off-by: Shuah Khan 
Tested-by: Mauro Carvalho Chehab 
Signed-off-by: Mauro Carvalho Chehab 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

media-device: dynamically allocate struct media_devnode

2020-04-28T18:03:50+00:00

commit a087ce704b802becbb4b0f2a20f2cb3f6911802e upstream.

struct media_devnode is currently embedded at struct media_device.

While this works fine during normal usage, it leads to a race
condition during devnode unregister. the problem is that drivers
assume that, after calling media_device_unregister(), the struct
that contains media_device can be freed. This is not true, as it
can't be freed until userspace closes all opened /dev/media devnodes.

In other words, if the media devnode is still open, and media_device
gets freed, any call to an ioctl will make the core to try to access
struct media_device, with will cause an use-after-free and even GPF.

Fix this by dynamically allocating the struct media_devnode and only
freeing it when it is safe.

Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Mauro Carvalho Chehab 
[bwh: Backported to 3.16:
 - Drop change in au0828
 - Include  in media-device.c
 - Adjust context]
Signed-off-by: Ben Hutchings

media-devnode: fix namespace mess

2020-04-28T18:03:49+00:00

commit 163f1e93e995048b894c5fc86a6034d16beed740 upstream.

Along all media controller code, "mdev" is used to represent
a pointer to struct media_device, and "devnode" for a pointer
to struct media_devnode.

However, inside media-devnode.[ch], "mdev" is used to represent
a pointer to struct media_devnode.

This is very confusing and may lead to development errors.

So, let's change all occurrences at media-devnode.[ch] to
also use "devnode" for such pointers.

This patch doesn't make any functional changes.

Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Mauro Carvalho Chehab 
[bwh: Backported to 3.16: adjust filename, context]
Signed-off-by: Ben Hutchings

media-devnode: add missing mutex lock in error handler

2020-04-28T18:03:49+00:00

commit 88336e174645948da269e1812f138f727cd2896b upstream.

We should protect the device unregister patch too, at the error
condition.

Signed-off-by: Max Kellermann 
Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Ben Hutchings

drivers/media/media-devnode: clear private_data before put_device()

2020-04-28T18:03:48+00:00

commit bf244f665d76d20312c80524689b32a752888838 upstream.

Callbacks invoked from put_device() may free the struct media_devnode
pointer, so any cleanup needs to be done before put_device().

Signed-off-by: Max Kellermann 
Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Ben Hutchings

media: Fix media_open() to clear filp->private_data in error leg

2020-04-28T18:03:48+00:00

commit d40ec6fdb0b03b7be4c7923a3da0e46bf943740a upstream.

Fix media_open() to clear filp->private_data when file open
fails.

Signed-off-by: Shuah Khan 
Acked-by: Sakari Ailus 
Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Ben Hutchings

media-devnode: just return 0 instead of using a var

2020-04-28T18:03:48+00:00

commit 8b37c6455fc8f43e0e95db2847284e618db6a4f8 upstream.

Instead of allocating a var to store 0 and just return it,
change the code to return 0 directly.

Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Ben Hutchings

media: xirlink_cit: add missing descriptor sanity checks

2020-04-28T18:03:44+00:00

commit a246b4d547708f33ff4d4b9a7a5dbac741dc89d8 upstream.

Make sure to check that we have two alternate settings and at least one
endpoint before accessing the second altsetting structure and
dereferencing the endpoint arrays.

This specifically avoids dereferencing NULL-pointers or corrupting
memory when a device does not have the expected descriptors.

Note that the sanity check in cit_get_packet_size() is not redundant as
the driver is mixing looking up altsettings by index and by number,
which may not coincide.

Fixes: 659fefa0eb17 ("V4L/DVB: gspca_xirlink_cit: Add support for camera with a bcd version of 0.01")
Fixes: 59f8b0bf3c12 ("V4L/DVB: gspca_xirlink_cit: support bandwidth changing for devices with 1 alt setting")
Cc: Hans de Goede 
Signed-off-by: Johan Hovold 
Signed-off-by: Hans Verkuil 
Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Ben Hutchings

media: stv06xx: add missing descriptor sanity checks

2020-04-28T18:03:44+00:00

commit 485b06aadb933190f4bc44e006076bc27a23f205 upstream.

Make sure to check that we have two alternate settings and at least one
endpoint before accessing the second altsetting structure and
dereferencing the endpoint arrays.

This specifically avoids dereferencing NULL-pointers or corrupting
memory when a device does not have the expected descriptors.

Note that the sanity checks in stv06xx_start() and pb0100_start() are
not redundant as the driver is mixing looking up altsettings by index
and by number, which may not coincide.

Fixes: 8668d504d72c ("V4L/DVB (12082): gspca_stv06xx: Add support for st6422 bridge and sensor")
Fixes: c0b33bdc5b8d ("[media] gspca-stv06xx: support bandwidth changing")
Cc: Hans de Goede 
Signed-off-by: Johan Hovold 
Signed-off-by: Hans Verkuil 
Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Ben Hutchings