diff options
| author | Dan Carpenter <dan.carpenter@oracle.com> | 2018-05-16 17:00:26 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-06-21 04:01:46 +0900 |
| commit | f6327d8039c7eeb686f8b3e06a8ce46f3c6e5db0 (patch) | |
| tree | db632db95c037b93e7013c1b9c9c1ef675bea14e | |
| parent | 2a164534b2ba7a13abc1e95e5abf3201885adc59 (diff) | |
drm/dumb-buffers: Integer overflow in drm_mode_create_ioctl()
[ Upstream commit 2b6207291b7b277a5df9d1aab44b56815a292dba ]
There is a comment here which says that DIV_ROUND_UP() and that's where
the problem comes from. Say you pick:
args->bpp = UINT_MAX - 7;
args->width = 4;
args->height = 1;
The integer overflow in DIV_ROUND_UP() means "cpp" is UINT_MAX / 8 and
because of how we picked args->width that means cpp < UINT_MAX / 4.
I've fixed it by preventing the integer overflow in DIV_ROUND_UP(). I
removed the check for !cpp because it's not possible after this change.
I also changed all the 0xffffffffU references to U32_MAX.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180516140026.GA19340@mwanda
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/gpu/drm/drm_dumb_buffers.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/gpu/drm/drm_dumb_buffers.c b/drivers/gpu/drm/drm_dumb_buffers.c index 39ac15ce4702..9e2ae02f31e0 100644 --- a/drivers/gpu/drm/drm_dumb_buffers.c +++ b/drivers/gpu/drm/drm_dumb_buffers.c @@ -65,12 +65,13 @@ int drm_mode_create_dumb_ioctl(struct drm_device *dev, return -EINVAL; /* overflow checks for 32bit size calculations */ - /* NOTE: DIV_ROUND_UP() can overflow */ + if (args->bpp > U32_MAX - 8) + return -EINVAL; cpp = DIV_ROUND_UP(args->bpp, 8); - if (!cpp || cpp > 0xffffffffU / args->width) + if (cpp > U32_MAX / args->width) return -EINVAL; stride = cpp * args->width; - if (args->height > 0xffffffffU / stride) + if (args->height > U32_MAX / stride) return -EINVAL; /* test for wrap-around */ |