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| author | Takashi Iwai <[email protected]> | 2018-04-02 20:41:43 +0000 |
|---|---|---|
| committer | Takashi Iwai <[email protected]> | 2018-04-03 06:36:40 +0000 |
| commit | a820ccbe21e8ce8e86c39cd1d3bc8c7d1cbb949b (patch) | |
| tree | e5b3fd50df32c9c9fa8b18f96079f5eb0a476888 /drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.c | |
| parent | Merge tag 'asoc-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/broon... (diff) | |
| download | kernel-a820ccbe21e8ce8e86c39cd1d3bc8c7d1cbb949b.tar.gz kernel-a820ccbe21e8ce8e86c39cd1d3bc8c7d1cbb949b.zip | |
ALSA: pcm: Fix UAF at PCM release via PCM timer access
The PCM runtime object is created and freed dynamically at PCM stream
open / close time. This is tracked via substream->runtime, and it's
cleared at snd_pcm_detach_substream().
The runtime object assignment is protected by PCM open_mutex, so for
all PCM operations, it's safely handled. However, each PCM substream
provides also an ALSA timer interface, and user-space can access to
this while closing a PCM substream. This may eventually lead to a
UAF, as snd_pcm_timer_resolution() tries to access the runtime while
clearing it in other side.
Fortunately, it's the only concurrent access from the PCM timer, and
it merely reads runtime->timer_resolution field. So, we can avoid the
race by reordering kfree() and wrapping the substream->runtime
clearance with the corresponding timer lock.
Reported-by: [email protected]
Cc: <[email protected]>
Signed-off-by: Takashi Iwai <[email protected]>
Diffstat (limited to 'drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.c')
0 files changed, 0 insertions, 0 deletions