[PATCH v4 2/3] drm/amd/display: Fix dangling pointer in CRTC reset function

[Evgenii Burenchev <evg28bur@yandex.ru>]

amdgpu_dm_crtc_reset_state() frees the old state before allocating
a new one. If kzalloc_obj() fails, the function returns without updating
the state pointer, leaving a dangling pointer to already freed memory.

Fix this by allocating the new state first. On allocation failure, the
old state remains untouched and the function safely returns.

Fixes: 473683a03495 ("drm/amd/display: Create a file dedicated for CRTC")
Signed-off-by: Evgenii Burenchev <evg28bur@yandex.ru>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
index 3dcedaa67ed8..5b5c4023a514 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
@@ -437,13 +437,13 @@ static void amdgpu_dm_crtc_reset_state(struct drm_crtc *crtc)
 {
 	struct dm_crtc_state *state;
 
-	if (crtc->state)
-		amdgpu_dm_crtc_destroy_state(crtc, crtc->state);
-
 	state = kzalloc_obj(*state);
-	if (WARN_ON(!state))
+	if (!state)
 		return;
 
+	if (crtc->state)
+		amdgpu_dm_crtc_destroy_state(crtc, crtc->state);
+
 	__drm_atomic_helper_crtc_reset(crtc, &state->base);
 }
 
-- 
2.43.0