drm/vc4: kms: Fix return code check

commit f927767978d201d4ac023fcd797adbb963a6565d upstream.

The HVS global state functions return an error pointer, but in most
cases we check if it's NULL, possibly resulting in an invalid pointer
dereference.

Fixes: 9ec03d7f1ed3 ("drm/vc4: kms: Wait on previous FIFO users before a commit")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Tested-by: Jian-Hong Pan <jhp@endlessos.org>
Link: https://lore.kernel.org/r/20211117094527.146275-3-maxime@cerno.tech
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 764ddb4..3f780c1 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -354,7 +354,7 @@ static void vc4_atomic_commit_tail(struct drm_atomic_state *state)
        }
 
        old_hvs_state = vc4_hvs_get_old_global_state(state);
-       if (!old_hvs_state)
+       if (IS_ERR(old_hvs_state))
                return;
 
        for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) {
@@ -410,8 +410,8 @@ static int vc4_atomic_commit_setup(struct drm_atomic_state *state)
        unsigned int i;
 
        hvs_state = vc4_hvs_get_new_global_state(state);
-       if (!hvs_state)
-               return -EINVAL;
+       if (WARN_ON(IS_ERR(hvs_state)))
+               return PTR_ERR(hvs_state);
 
        for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
                struct vc4_crtc_state *vc4_crtc_state =
@@ -762,8 +762,8 @@ static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
        unsigned int i;
 
        hvs_new_state = vc4_hvs_get_global_state(state);
-       if (!hvs_new_state)
-               return -EINVAL;
+       if (IS_ERR(hvs_new_state))
+               return PTR_ERR(hvs_new_state);
 
        for (i = 0; i < ARRAY_SIZE(hvs_new_state->fifo_state); i++)
                if (!hvs_new_state->fifo_state[i].in_use)