linux-kernel - [PATCH] drm/nouveau/disp: fix use-after-free in error handling of nouveau_connector

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Date:   Mon, 14 Aug 2023 16:49:32 +0200
From:   Karol Herbst <kherbst@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Ben Skeggs <bskeggs@...hat.com>, Lyude Paul <lyude@...hat.com>,
        dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        Borislav Petkov <bp@...en8.de>, Takashi Iwai <tiwai@...e.de>,
        Karol Herbst <kherbst@...hat.com>
Subject: [PATCH] drm/nouveau/disp: fix use-after-free in error handling of nouveau_connector_create

We can't simply free the connector after calling drm_connector_init on it.
We need to clean up the drm side first.

It might not fix all regressions from 2b5d1c29f6c4 ("drm/nouveau/disp:
PIOR DP uses GPIO for HPD, not PMGR AUX interrupts"), but at least it
fixes a memory corruption in error handling related to that commit.

Link: https://lore.kernel.org/lkml/20230806213107.GFZNARG6moWpFuSJ9W@fat_crate.local/
Fixes: 95983aea8003 ("drm/nouveau/disp: add connector class")
Signed-off-by: Karol Herbst <kherbst@...hat.com>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index a2e0033e8a260..622f6eb9a8bfd 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -1408,8 +1408,7 @@ nouveau_connector_create(struct drm_device *dev,
 		ret = nvif_conn_ctor(&disp->disp, nv_connector->base.name, nv_connector->index,
 				     &nv_connector->conn);
 		if (ret) {
-			kfree(nv_connector);
-			return ERR_PTR(ret);
+			goto drm_conn_err;
 		}
 
 		ret = nvif_conn_event_ctor(&nv_connector->conn, "kmsHotplug",
@@ -1426,8 +1425,7 @@ nouveau_connector_create(struct drm_device *dev,
 			if (ret) {
 				nvif_event_dtor(&nv_connector->hpd);
 				nvif_conn_dtor(&nv_connector->conn);
-				kfree(nv_connector);
-				return ERR_PTR(ret);
+				goto drm_conn_err;
 			}
 		}
 	}
@@ -1475,4 +1473,9 @@ nouveau_connector_create(struct drm_device *dev,
 
 	drm_connector_register(connector);
 	return connector;
+
+drm_conn_err:
+	drm_connector_cleanup(connector);
+	kfree(nv_connector);
+	return ERR_PTR(ret);
 }
-- 
2.41.0