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 <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Cc: Chris Wilson <[email protected]>
Cc: Matthew Auld <[email protected]>
Reviewed-by: Chris Wilson <[email protected]>
Signed-off-by: Chris Wilson <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
register lookup")
(cherry picked from commit 2f265fad9756a40c09e3f4dcc62d5d7fa73a9fb2)
Signed-off-by: Rodrigo Vivi <[email protected]>

0 files changed, 0 insertions, 0 deletions