drm/i915/cmdparser: Check reg_table_count before derefencing.
commit 2f265fad9756a40c09e3f4dcc62d5d7fa73a9fb2 upstream.
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")
Reviewed-by: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c
index cd124df..d844ab0 100644
--- a/drivers/gpu/drm/i915/i915_cmd_parser.c
+++ b/drivers/gpu/drm/i915/i915_cmd_parser.c
@@ -1038,7 +1038,7 @@
const struct drm_i915_reg_table *table = engine->reg_tables;
int count = engine->reg_table_count;
- do {
+ for (; count > 0; ++table, --count) {
if (!table->master || is_master) {
const struct drm_i915_reg_descriptor *reg;
@@ -1046,7 +1046,7 @@
if (reg != NULL)
return reg;
}
- } while (table++, --count);
+ }
return NULL;
}