[PATCH 5.15 140/207] drm/vc4: kms: Fix return code check

[Greg Kroah-Hartman]

From: Maxime Ripard <maxime@xxxxxxxxxx>

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@xxxxxxxxxx>
Reviewed-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
Tested-by: Jian-Hong Pan <jhp@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211117094527.146275-3-maxime@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/vc4/vc4_kms.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- 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(struc
 	}
 
 	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(struc
 	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(st
 	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)