From 00e7208997d7a42b6f7b22f582523755f43a2f9b Mon Sep 17 00:00:00 2001 From: David Herrmann Date: Sun, 24 Aug 2014 19:23:26 +0200 Subject: [PATCH] drm: fix division-by-zero on dumb_create() Kinda unexpected, but DIV_ROUND_UP() can overflow if passed an argument bigger than UINT_MAX - DIVISOR. Fix this by testing for "!cpp" before using it in the following division. Note that DIV_ROUND_UP() is defined as: #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d)) ..this will obviously overflow if (n + d - 1) is bigger than UINT_MAX. Reported-by: Tommi Rantala Signed-off-by: David Herrmann Reviewed-by: Rob Clark Signed-off-by: Dave Airlie --- drivers/gpu/drm/drm_crtc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index fa2be24..90e7730 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -4696,8 +4696,9 @@ int drm_mode_create_dumb_ioctl(struct drm_device *dev, return -EINVAL; /* overflow checks for 32bit size calculations */ + /* NOTE: DIV_ROUND_UP() can overflow */ cpp = DIV_ROUND_UP(args->bpp, 8); - if (cpp > 0xffffffffU / args->width) + if (!cpp || cpp > 0xffffffffU / args->width) return -EINVAL; stride = cpp * args->width; if (args->height > 0xffffffffU / stride) -- 2.7.4