commit 56b88b50565cd8b946a2d00b0c83927b7ebb055e upstream.
Takes rwsem lock inside snd_ctl_elem_read instead of snd_ctl_elem_read_user
like it was done for write in commit 1fa4445f9a ("ALSA: control - introduce
snd_ctl_notify_one() helper"). Doing this way we are also fixing the following
locking issue happening in the compat path which can be easily triggered and
turned into an use-after-free.
64-bits:
snd_ctl_ioctl
snd_ctl_elem_read_user
[takes controls_rwsem]
snd_ctl_elem_read [lock properly held, all good]
[drops controls_rwsem]
32-bits:
snd_ctl_ioctl_compat
snd_ctl_elem_write_read_compat
ctl_elem_write_read
snd_ctl_elem_read [missing lock, not good]
CVE-2023-0266 was assigned for this issue.
Cc: stable@kernel.org # 5.13+
Signed-off-by: Clement Lecigne <clecigne@google.com>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230113120745.25464-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
26350c21bc