[PATCH 3.15 048/122] drm: fix NULL pointer access by wrong ioctl

From: Greg Kroah-Hartman
Date: Mon Jul 07 2014 - 21:08:39 EST


3.15-stable review patch. If anyone has any objections, please let me know.

------------------

From: Zhaowei Yuan <zhaowei.yuan@xxxxxxxxxxx>

commit 1539fb9bd405ee32282ea0a38404f9e008ac5b7a upstream.

If user uses wrong ioctl command with _IOC_NONE and argument size
greater than 0, it can cause NULL pointer access from memset of line
463. If _IOC_NONE, don't memset to 0 for kdata.

Signed-off-by: Zhaowei Yuan <zhaowei.yuan@xxxxxxxxxxx>
Reviewed-by: David Herrmann <dh.herrmann@xxxxxxxxx>
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/gpu/drm/drm_drv.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -419,8 +419,9 @@ long drm_ioctl(struct file *filp,
retcode = -EFAULT;
goto err_i1;
}
- } else
+ } else if (cmd & IOC_OUT) {
memset(kdata, 0, usize);
+ }

if (ioctl->flags & DRM_UNLOCKED)
retcode = func(dev, kdata, file_priv);


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