linux-kernel - [PATCH 3.10 221/268] drm/vmwgfx: avoid calling vzalloc with a 0 size in vmw_get_cap_3d

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Message-Id: <1497897167-14556-222-git-send-email-w@1wt.eu>
Date:   Mon, 19 Jun 2017 20:32:00 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Murray McAllister <murray.mcallister@...omniasec.com>,
        Jiri Slaby <jslaby@...e.cz>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 221/268] drm/vmwgfx: avoid calling vzalloc with a 0 size in vmw_get_cap_3d_ioctl()

From: Murray McAllister <murray.mcallister@...omniasec.com>

commit 63774069d9527a1aeaa4aa20e929ef5e8e9ecc38 upstream.

In vmw_get_cap_3d_ioctl(), a user can supply 0 for a size that is
used in vzalloc(). This eventually calls dump_stack() (in warn_alloc()),
which can leak useful addresses to dmesg.

Add check to avoid a size of 0.

Signed-off-by: Murray McAllister <murray.mcallister@...omniasec.com>
Reviewed-by: Sinclair Yeh <syeh@...are.com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
index c509d40..f435b6c 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
@@ -90,7 +90,7 @@ int vmw_get_cap_3d_ioctl(struct drm_device *dev, void *data,
 	void *bounce;
 	int ret;
 
-	if (unlikely(arg->pad64 != 0)) {
+	if (unlikely(arg->pad64 != 0 || arg->max_size == 0)) {
 		DRM_ERROR("Illegal GET_3D_CAP argument.\n");
 		return -EINVAL;
 	}
-- 
2.8.0.rc2.1.gbe9624a