Tuomas Tynkkynen e30cc79cc8 media: media-request: Fix crash if memory allocation fails ... Syzbot reports a NULL-ptr deref in the kref_put() call: BUG: KASAN: null-ptr-deref in media_request_put drivers/media/mc/mc-request.c:81 [inline] kref_put include/linux/kref.h:64 [inline] media_request_put drivers/media/mc/mc-request.c:81 [inline] media_request_close+0x4d/0x170 drivers/media/mc/mc-request.c:89 __fput+0x2ed/0x750 fs/file_table.c:281 task_work_run+0x147/0x1d0 kernel/task_work.c:123 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:165 [inline] prepare_exit_to_usermode+0x48e/0x600 arch/x86/entry/common.c:196 What led to this crash was an injected memory allocation failure in media_request_alloc(): FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 should_failslab+0x5/0x20 kmem_cache_alloc_trace+0x57/0x300 ? anon_inode_getfile+0xe5/0x170 media_request_alloc+0x339/0x440 media_device_request_alloc+0x94/0xc0 media_device_ioctl+0x1fb/0x330 ? do_vfs_ioctl+0x6ea/0x1a00 ? media_ioctl+0x101/0x120 ? __media_device_usb_init+0x430/0x430 ? media_poll+0x110/0x110 __se_sys_ioctl+0xf9/0x160 do_syscall_64+0xf3/0x1b0 When that allocation fails, filp->private_data is left uninitialized which media_request_close() does not expect and crashes. To avoid this, reorder media_request_alloc() such that allocating the struct file happens as the last step thus media_request_close() will no longer get called for a partially created media request. Reported-by: syzbot+6bed2d543cf7e48b822b@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi> Fixes: 10905d70d7 ("media: media-request: implement media requests") Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>		2020-06-23 15:19:37 +02:00
..
Kconfig	media: mc/Kconfig: remove staging dependency for request API	2020-04-17 08:57:39 +02:00
Makefile
mc-dev-allocator.c
mc-device.c
mc-devnode.c
mc-entity.c	media: entity: Pass entity to get_fwnode_pad operation	2020-05-18 11:12:05 +02:00
mc-request.c	media: media-request: Fix crash if memory allocation fails	2020-06-23 15:19:37 +02:00