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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: 351e3db2b3 ("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
This commit is contained in:
Michal Srb 2018-02-05 16:04:38 +00:00 committed by Chris Wilson
parent 2f265fad97
commit 3aec7f871c
1 changed files with 6 additions and 0 deletions
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6
drivers/gpu/drm/i915/i915_cmd_parser.c
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@ -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;