[PATCH 4.9 10/25] ALSA: wavefront: Proper check of get_user() error

[Greg Kroah-Hartman]

From: Takashi Iwai <tiwai@xxxxxxx>

commit a34ae6c0660d3b96b0055f68ef74dc9478852245 upstream.

The antient ISA wavefront driver reads its sample patch data (uploaded
over an ioctl) via __get_user() with no good reason; likely just for
some performance optimizations in the past.  Let's change this to the
standard get_user() and the error check for handling the fault case
properly.

Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220510103626.16635-1-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 sound/isa/wavefront/wavefront_synth.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/sound/isa/wavefront/wavefront_synth.c
+++ b/sound/isa/wavefront/wavefront_synth.c
@@ -1091,7 +1091,8 @@ wavefront_send_sample (snd_wavefront_t *
 
 			if (dataptr < data_end) {
 		
-				__get_user (sample_short, dataptr);
+				if (get_user(sample_short, dataptr))
+					return -EFAULT;
 				dataptr += skip;
 		
 				if (data_is_unsigned) { /* GUS ? */