3.16.60-rc1 review patch. If anyone has any objections, please let me know.
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From: Michal Srb msrb@suse.com
commit 3aec7f871c65eb5f76b4125fda432593c834a6f2 upstream.
The command MEDIA_VFE_STATE checks bits at offset +2 dwords. However, it is possible to have MEDIA_VFE_STATE command with length = 0 + LENGTH_BIAS = 2. In that case check_cmd will read bits from the following command, or even past the end of the buffer.
If the offset ends up outside of the command length, reject the command.
Fixes: 351e3db2b363 ("drm/i915: Implement command buffer parsing logic") Signed-off-by: Michal Srb msrb@suse.com Link: https://patchwork.freedesktop.org/patch/msgid/20180205151745.29292-1-msrb@su... Reviewed-by: Chris Wilson chris@chris-wilson.co.uk Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Link: https://patchwork.freedesktop.org/patch/msgid/20180205160438.3267-2-chris@ch... [bwh: Backported to 3.16: Log ring->id rather than engine->name] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/gpu/drm/i915/i915_cmd_parser.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/drivers/gpu/drm/i915/i915_cmd_parser.c +++ b/drivers/gpu/drm/i915/i915_cmd_parser.c @@ -941,6 +941,12 @@ static bool check_cmd(const struct intel continue; }
+ if (desc->bits[i].offset >= length) { + DRM_DEBUG_DRIVER("CMD: Rejected command 0x%08X, too short to check bitmask (ring=%d)\n", + *cmd, ring->id); + return false; + } + dword = cmd[desc->bits[i].offset] & desc->bits[i].mask;