kernel/linux.git/drivers/media/media-devnode.c, branch v4.4.235

media: fix media devnode ioctl/syscall and unregister race

2020-05-27T14:40:25+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 4.4: adjut filename, context] Signed-off-by: Ben Hutchings Signed-off-by: Sasha Levin

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

2020-05-27T14:40:25+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 Signed-off-by: Ben Hutchings Signed-off-by: Sasha Levin

media-device: dynamically allocate struct media_devnode

2020-05-27T14:40:25+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 4.4: - Drop change in au0828 - Include in media-device.c - Adjust context] Signed-off-by: Ben Hutchings Signed-off-by: Sasha Levin

media-devnode: fix namespace mess

2020-05-27T14:40:25+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 4.4: adjust filename, context] Signed-off-by: Ben Hutchings Signed-off-by: Sasha Levin

media-devnode: add missing mutex lock in error handler

2020-05-27T14:40:24+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 Signed-off-by: Sasha Levin

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

2020-05-27T14:40:24+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 Signed-off-by: Sasha Levin

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

2020-05-27T14:40:24+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 Signed-off-by: Sasha Levin

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

2014-09-03T20:59:28+00:00

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

[media] media: Use a better owner for the media device

2014-05-13T16:39:00+00:00

mdev->fops->owner is actually the owner of the very same module which implements media_device_register(), so it can't be unloaded anyway. Instead, use THIS_MODULE through a macro as does video_register_device(). Signed-off-by: Sakari Ailus Acked-by: Laurent Pinchart Signed-off-by: Mauro Carvalho Chehab

[media] media: Add 64--32 bit compat ioctl handler

2013-03-18T23:44:36+00:00

Provide an ioctl handler for 32-bit binaries on 64-bit systems. Signed-off-by: Sakari Ailus Acked-by: Laurent Pinchart Tested-by: Laurent Pinchart Signed-off-by: Mauro Carvalho Chehab