diff options
| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2018-10-16 12:55:49 +0300 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2018-10-17 10:17:33 +0300 |
| commit | a37805098900a6e73a55b3a43b7d3bcd987bb3f4 (patch) | |
| tree | fb8997e7e2a942d262a63e6f99deb1b037ae3bfe | |
| parent | 871edc96bdab5fd84134320456670e7bfd5ec31a (diff) | |
| download | linux-a37805098900a6e73a55b3a43b7d3bcd987bb3f4.tar.xz | |
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
| -rw-r--r-- | drivers/gpu/drm/drm_bufs.c | 3 |
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", |