drm/i915/cmdparser: Check reg_table_count before derefencing.
authorMichal Srb <msrb@suse.com>
Mon, 5 Feb 2018 16:04:37 +0000 (16:04 +0000)
committerChris Wilson <chris@chris-wilson.co.uk>
Mon, 5 Feb 2018 20:49:14 +0000 (20:49 +0000)
commit2f265fad9756a40c09e3f4dcc62d5d7fa73a9fb2
tree186054b2aa3960900161db7a93d43bcb3fe09f34
parent6ec5bd348934887494541bcc9b53d621b1f2962c
drm/i915/cmdparser: Check reg_table_count before derefencing.

The find_reg function was assuming that there is always at least one table in
reg_tables. It is not always true.

In case of VCS or VECS, the reg_tables is NULL and reg_table_count is 0,
implying that no register-accessing commands are allowed. However, the command
tables include commands such as MI_STORE_REGISTER_MEM. When trying to check
such command, the find_reg would dereference NULL pointer.

Now it will just return NULL meaning that the register was not found and the
command will be rejected.

Fixes: 76ff480ec963 ("drm/i915/cmdparser: Use binary search for faster register lookup")
Signed-off-by: Michal Srb <msrb@suse.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180205142916.27092-2-msrb@suse.com
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.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/20180205160438.3267-1-chris@chris-wilson.co.uk
register lookup")
drivers/gpu/drm/i915/i915_cmd_parser.c