summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorGustavo A. R. Silva <gustavo@embeddedor.com>2018-12-19 18:00:15 -0600
committerDaniel Vetter <daniel.vetter@ffwll.ch>2018-12-20 08:13:29 +0100
commit505b5240329b922f21f91d5b5d1e535c805eca6d (patch)
tree6ea8716b486fbe05a8b12de38d9ed814fcdbb1b3
parent7566ec393f4161572ba6f11ad5171fd5d59b0fbd (diff)
drm/ioctl: Fix Spectre v1 vulnerabilitiesdrm-misc-fixes-2018-12-20
nr is 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_ioctl.c:805 drm_ioctl() warn: potential spectre issue 'dev->driver->ioctls' [r] drivers/gpu/drm/drm_ioctl.c:810 drm_ioctl() warn: potential spectre issue 'drm_ioctls' [r] (local cap) drivers/gpu/drm/drm_ioctl.c:892 drm_ioctl_flags() warn: potential spectre issue 'drm_ioctls' [r] (local cap) Fix this by sanitizing nr before using it to index dev->driver->ioctls and drm_ioctls. 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 Cc: stable@vger.kernel.org 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/20181220000015.GA18973@embeddedor
-rw-r--r--drivers/gpu/drm/drm_ioctl.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index 94bd872d56c4..7e6746b2d704 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -37,6 +37,7 @@
#include <linux/pci.h>
#include <linux/export.h>
+#include <linux/nospec.h>
/**
* DOC: getunique and setversion story
@@ -800,13 +801,17 @@ long drm_ioctl(struct file *filp,
if (is_driver_ioctl) {
/* driver ioctl */
- if (nr - DRM_COMMAND_BASE >= dev->driver->num_ioctls)
+ unsigned int index = nr - DRM_COMMAND_BASE;
+
+ if (index >= dev->driver->num_ioctls)
goto err_i1;
- ioctl = &dev->driver->ioctls[nr - DRM_COMMAND_BASE];
+ index = array_index_nospec(index, dev->driver->num_ioctls);
+ ioctl = &dev->driver->ioctls[index];
} else {
/* core ioctl */
if (nr >= DRM_CORE_IOCTL_COUNT)
goto err_i1;
+ nr = array_index_nospec(nr, DRM_CORE_IOCTL_COUNT);
ioctl = &drm_ioctls[nr];
}
@@ -888,6 +893,7 @@ bool drm_ioctl_flags(unsigned int nr, unsigned int *flags)
if (nr >= DRM_CORE_IOCTL_COUNT)
return false;
+ nr = array_index_nospec(nr, DRM_CORE_IOCTL_COUNT);
*flags = drm_ioctls[nr].flags;
return true;