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* [PATCH AUTOSEL 4.14 001/170] drm/bufs: Fix Spectre v1 vulnerability
@ 2019-01-28 16:09 Sasha Levin
  2019-01-28 16:09 ` [PATCH AUTOSEL 4.14 003/170] drm/vgem: Fix vgem_init to get drm device available Sasha Levin
                   ` (7 more replies)
  0 siblings, 8 replies; 9+ messages in thread
From: Sasha Levin @ 2019-01-28 16:09 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Gustavo A. R. Silva, Daniel Vetter, Sasha Levin, dri-devel

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>

[ Upstream commit a37805098900a6e73a55b3a43b7d3bcd987bb3f4 ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/drm_bufs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c
index 1ee84dd802d4..0f05b8d8fefa 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",
-- 
2.19.1

^ permalink raw reply related	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2019-01-28 16:17 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2019-01-28 16:09 [PATCH AUTOSEL 4.14 001/170] drm/bufs: Fix Spectre v1 vulnerability Sasha Levin
2019-01-28 16:09 ` [PATCH AUTOSEL 4.14 003/170] drm/vgem: Fix vgem_init to get drm device available Sasha Levin
2019-01-28 16:09 ` [PATCH AUTOSEL 4.14 006/170] gpu: ipu-v3: image-convert: Prevent race between run and unprepare Sasha Levin
2019-01-28 16:09 ` [PATCH AUTOSEL 4.14 019/170] drm/vc4: ->x_scaling[1] should never be set to VC4_SCALING_NONE Sasha Levin
     [not found] ` <20190128161200.55107-1-sashal-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2019-01-28 16:09   ` [PATCH AUTOSEL 4.14 030/170] drm/rockchip: fix for mailbox read size Sasha Levin
2019-01-28 16:10 ` [PATCH AUTOSEL 4.14 054/170] drm: Clear state->acquire_ctx before leaving drm_atomic_helper_commit_duplicated_state() Sasha Levin
2019-01-28 16:11 ` [PATCH AUTOSEL 4.14 127/170] video: clps711x-fb: release disp device node in probe() Sasha Levin
2019-01-28 16:11 ` [PATCH AUTOSEL 4.14 129/170] fbdev: fbmem: behave better with small rotated displays and many CPUs Sasha Levin
2019-01-28 16:11 ` [PATCH AUTOSEL 4.14 133/170] fbdev: fbcon: Fix unregister crash when more than one framebuffer Sasha Levin

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