Re: [PATCH v2 4.4] ALSA: seq: Make ioctls race-free

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, Jan 31, 2018 at 06:06:09PM +0000, Ben Hutchings wrote:
> From: Takashi Iwai <tiwai@xxxxxxx>
> 
> commit b3defb791b26ea0683a93a4f49c77ec45ec96f10 upstream.
> 
> The ALSA sequencer ioctls have no protection against racy calls while
> the concurrent operations may lead to interfere with each other.  As
> reported recently, for example, the concurrent calls of setting client
> pool with a combination of write calls may lead to either the
> unkillable dead-lock or UAF.
> 
> As a slightly big hammer solution, this patch introduces the mutex to
> make each ioctl exclusive.  Although this may reduce performance via
> parallel ioctl calls, usually it's not demanded for sequencer usages,
> hence it should be negligible.
> 
> Reported-by: Luo Quan <a4651386@xxxxxxx>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
> [bwh: Backported to 4.4: ioctl dispatch is done from snd_seq_do_ioctl();
>  take the mutex and add ret variable there.]

Thanks for the backport, now applied.

greg k-h



[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]