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@xxxxxxxxxx> --- v2: additional cleanups 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 */ -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
