wavefront_fx.c utilizes memdup_user() to copy a userspace array. This
does not check for an overflow.

Use the new wrapper memdup_array_user() to copy the array more safely.

Suggested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
 sound/isa/wavefront/wavefront_fx.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/isa/wavefront/wavefront_fx.c b/sound/isa/wavefront/wavefront_fx.c
index 3c21324b2a0e..0273b7dfaf12 100644
--- a/sound/isa/wavefront/wavefront_fx.c
+++ b/sound/isa/wavefront/wavefront_fx.c
@@ -191,9 +191,9 @@ snd_wavefront_fx_ioctl (struct snd_hwdep *sdev, struct file *file,
 					    "> 512 bytes to FX\n");
 				return -EIO;
 			}
-			page_data = memdup_user((unsigned char __user *)
-						r.data[3],
-						r.data[2] * sizeof(short));
+			page_data = memdup_array_user((unsigned char __user *)
+						      r.data[3],
+						      r.data[2], sizeof(short));
 			if (IS_ERR(page_data))
 				return PTR_ERR(page_data);
 			pd = page_data;
-- 
2.41.0

On Thu, 02 Nov 2023 20:03:10 +0100,
Philipp Stanner wrote:
> 
> wavefront_fx.c utilizes memdup_user() to copy a userspace array. This
> does not check for an overflow.

There is a check above the memdup_user() call; it's at most 512
bytes.

> Use the new wrapper memdup_array_user() to copy the array more safely.
> 
> Suggested-by: Dave Airlie <airlied@redhat.com>
> Signed-off-by: Philipp Stanner <pstanner@redhat.com>

Although the check is already present, it's still better to use the
new helper, so I applied the patch now.


thanks,

Takashi

On Fri, 03 Nov 2023 14:58:22 +0100,
Takashi Iwai wrote:
> 
> On Thu, 02 Nov 2023 20:03:10 +0100,
> Philipp Stanner wrote:
> > 
> > wavefront_fx.c utilizes memdup_user() to copy a userspace array. This
> > does not check for an overflow.
> 
> There is a check above the memdup_user() call; it's at most 512
> bytes.
> 
> > Use the new wrapper memdup_array_user() to copy the array more safely.
> > 
> > Suggested-by: Dave Airlie <airlied@redhat.com>
> > Signed-off-by: Philipp Stanner <pstanner@redhat.com>
> 
> Although the check is already present, it's still better to use the
> new helper, so I applied the patch now.

... and the helper is available only on Linus tree for now, so I
postpone after 6.7-rc1 release, so that we can have a solid base.


Takashi