[PATCH 4.9 17/91] drm: limit to INT_MAX in create_blob ioctl

[Greg Kroah-Hartman]

From: Daniel Vetter <daniel.vetter@xxxxxxxx>

[ Upstream commit 5bf8bec3f4ce044a223c40cbce92590d938f0e9c ]

The hardened usercpy code is too paranoid ever since commit 6a30afa8c1fb
("uaccess: disallow > INT_MAX copy sizes")

Code itself should have been fine as-is.

Link: http://lkml.kernel.org/r/20191106164755.31478-1-daniel.vetter@xxxxxxxx
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Reported-by: syzbot+fb77e97ebf0612ee6914@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 6a30afa8c1fb ("uaccess: disallow > INT_MAX copy sizes")
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/drm_property.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_property.c b/drivers/gpu/drm/drm_property.c
index a4d81cf4ffa0..16c72d2ddc2e 100644
--- a/drivers/gpu/drm/drm_property.c
+++ b/drivers/gpu/drm/drm_property.c
@@ -554,7 +554,7 @@ drm_property_create_blob(struct drm_device *dev, size_t length,
 	struct drm_property_blob *blob;
 	int ret;
 
-	if (!length || length > ULONG_MAX - sizeof(struct drm_property_blob))
+	if (!length || length > INT_MAX - sizeof(struct drm_property_blob))
 		return ERR_PTR(-EINVAL);
 
 	blob = kzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL);
-- 
2.20.1