Clement Lecigne
56b88b5056
ALSA: pcm: Move rwsem lock inside snd_ctl_elem_read to prevent UAF
Takes rwsem lock inside snd_ctl_elem_read instead of snd_ctl_elem_read_user like it was done for write in commit 1fa4445f9adf1 ("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>
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