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| author | Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi> | 2020-06-21 13:30:40 +0200 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2020-06-23 15:19:37 +0200 |
| commit | e30cc79cc80fd919b697a15c5000d9f57487de8e (patch) | |
| tree | ba6a940145896ef8b12f417d3ef7157e7c40699f /drivers/media/mc/mc-request.c | |
| parent | 7b981288285f0e8b816ea7ba8f34d0973ee39e0d (diff) | |
| download | linux-e30cc79cc80fd919b697a15c5000d9f57487de8e.tar.bz2 | |
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: 10905d70d788 ("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>
Diffstat (limited to 'drivers/media/mc/mc-request.c')
| -rw-r--r-- | drivers/media/mc/mc-request.c | 31 |
1 files changed, 17 insertions, 14 deletions
diff --git a/drivers/media/mc/mc-request.c b/drivers/media/mc/mc-request.c index e3fca436c75b..c0782fd96c59 100644 --- a/drivers/media/mc/mc-request.c +++ b/drivers/media/mc/mc-request.c @@ -296,9 +296,18 @@ int media_request_alloc(struct media_device *mdev, int *alloc_fd) if (WARN_ON(!mdev->ops->req_alloc ^ !mdev->ops->req_free)) return -ENOMEM; + if (mdev->ops->req_alloc) + req = mdev->ops->req_alloc(mdev); + else + req = kzalloc(sizeof(*req), GFP_KERNEL); + if (!req) + return -ENOMEM; + fd = get_unused_fd_flags(O_CLOEXEC); - if (fd < 0) - return fd; + if (fd < 0) { + ret = fd; + goto err_free_req; + } filp = anon_inode_getfile("request", &request_fops, NULL, O_CLOEXEC); if (IS_ERR(filp)) { @@ -306,15 +315,6 @@ int media_request_alloc(struct media_device *mdev, int *alloc_fd) goto err_put_fd; } - if (mdev->ops->req_alloc) - req = mdev->ops->req_alloc(mdev); - else - req = kzalloc(sizeof(*req), GFP_KERNEL); - if (!req) { - ret = -ENOMEM; - goto err_fput; - } - filp->private_data = req; req->mdev = mdev; req->state = MEDIA_REQUEST_STATE_IDLE; @@ -336,12 +336,15 @@ int media_request_alloc(struct media_device *mdev, int *alloc_fd) return 0; -err_fput: - fput(filp); - err_put_fd: put_unused_fd(fd); +err_free_req: + if (mdev->ops->req_free) + mdev->ops->req_free(req); + else + kfree(req); + return ret; } |