From 3aec7f871c65eb5f76b4125fda432593c834a6f2 Mon Sep 17 00:00:00 2001 From: Michal Srb Date: Mon, 5 Feb 2018 16:04:38 +0000 Subject: [PATCH] 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: 351e3db2b363 ("drm/i915: Implement command buffer parsing logic") Signed-off-by: Michal Srb Link: https://patchwork.freedesktop.org/patch/msgid/20180205151745.29292-1-msrb@suse.com Reviewed-by: Chris Wilson Signed-off-by: Chris Wilson Link: https://patchwork.freedesktop.org/patch/msgid/20180205160438.3267-2-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_cmd_parser.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c index ab4c8b0ec886..95478db9998b 100644 --- a/drivers/gpu/drm/i915/i915_cmd_parser.c +++ b/drivers/gpu/drm/i915/i915_cmd_parser.c @@ -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; -- 2.30.2