Commit b3ad99ed authored Feb 05, 2018 by Michal Srb Committed by Rodrigo Vivi Feb 06, 2018

drm/i915/cmdparser: Do not check past the cmd length.



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: 351e3db2 ("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@suse.com


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@chris-wilson.co.uk


(cherry picked from commit 3aec7f87)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

parent b18224e9

drivers/gpu/drm/i915/i915_cmd_parser.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -1212,6 +1212,12 @@ static bool check_cmd(const struct intel_engine_cs *engine,
		continue;
		}

		if (desc->bits[i].offset >= length) {
		DRM_DEBUG_DRIVER("CMD: Rejected command 0x%08X, too short to check bitmask (%s)\n",
		*cmd, engine->name);
		return false;
		}

		dword = cmd[desc->bits[i].offset] &
		desc->bits[i].mask;