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authorGustavo A. R. Silva <gustavo@embeddedor.com>2018-10-16 11:55:49 +0200
committerDaniel Vetter <daniel.vetter@ffwll.ch>2018-10-17 09:17:33 +0200
commita37805098900a6e73a55b3a43b7d3bcd987bb3f4 (patch)
treefb8997e7e2a942d262a63e6f99deb1b037ae3bfe /drivers/gpu/drm/drm_bufs.c
parent871edc96bdab5fd84134320456670e7bfd5ec31a (diff)
drm/bufs: Fix Spectre v1 vulnerability
idx can be indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/gpu/drm/drm_bufs.c:1420 drm_legacy_freebufs() warn: potential spectre issue 'dma->buflist' [r] (local cap) Fix this by sanitizing idx before using it to index dma->buflist Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20181016095549.GA23586@embeddedor.com
Diffstat (limited to 'drivers/gpu/drm/drm_bufs.c')
-rw-r--r--drivers/gpu/drm/drm_bufs.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c
index 7412acaf3cde..d7d10cabb9bb 100644
--- a/drivers/gpu/drm/drm_bufs.c
+++ b/drivers/gpu/drm/drm_bufs.c
@@ -36,6 +36,8 @@
#include <drm/drmP.h>
#include "drm_legacy.h"
+#include <linux/nospec.h>
+
static struct drm_map_list *drm_find_matching_map(struct drm_device *dev,
struct drm_local_map *map)
{
@@ -1417,6 +1419,7 @@ int drm_legacy_freebufs(struct drm_device *dev, void *data,
idx, dma->buf_count - 1);
return -EINVAL;
}
+ idx = array_index_nospec(idx, dma->buf_count);
buf = dma->buflist[idx];
if (buf->file_priv != file_priv) {
DRM_ERROR("Process %d freeing buffer not owned\n",