drm: limit to INT_MAX in create_blob ioctl

[ 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@ffwll.ch
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reported-by: syzbot+fb77e97ebf0612ee6914@syzkaller.appspotmail.com
Fixes: 6a30afa8c1fb ("uaccess: disallow > INT_MAX copy sizes")
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/drm_property.c b/drivers/gpu/drm/drm_property.c
index cdb10f8..69dfed5 100644 (file)
--- a/drivers/gpu/drm/drm_property.c
+++ b/drivers/gpu/drm/drm_property.c
@@ -556,7 +556,7 @@ 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 = kvzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL);