linux-kernel - [PATCH RFC 23/33] drm: bridge: cdns-mhdp8546: Fix a locking bug in an error path

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Message-ID: <20250206175114.1974171-24-bvanassche@acm.org>
Date: Thu,  6 Feb 2025 09:51:04 -0800
From: Bart Van Assche <bvanassche@....org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Will Deacon <will@...nel.org>,
	Christoph Hellwig <hch@....de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Marco Elver <elver@...gle.com>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Nathan Chancellor <nathan@...nel.org>,
	Kees Cook <kees@...nel.org>,
	Jann Horn <jannh@...gle.com>,
	linux-kernel@...r.kernel.org,
	Bart Van Assche <bvanassche@....org>,
	Aleksandr Mishin <amishin@...rgos.ru>,
	Robert Foss <rfoss@...nel.org>
Subject: [PATCH RFC 23/33] drm: bridge: cdns-mhdp8546: Fix a locking bug in an error path

Unlock mhdp->link_mutex before returning.

This bug has been detected by the Clang thread-safety analyzer.

Cc: Aleksandr Mishin <amishin@...rgos.ru>
Cc: Robert Foss <rfoss@...nel.org>
Fixes: 935a92a1c400 ("drm: bridge: cdns-mhdp8546: Fix possible null pointer dereference")
Signed-off-by: Bart Van Assche <bvanassche@....org>
---
 drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 9295b2a9f9be..51e2caa9c815 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2053,8 +2053,10 @@ static void cdns_mhdp_atomic_enable(struct drm_bridge *bridge,
 	mhdp_state = to_cdns_mhdp_bridge_state(new_state);
 
 	mhdp_state->current_mode = drm_mode_duplicate(bridge->dev, mode);
-	if (!mhdp_state->current_mode)
-		return;
+	if (!mhdp_state->current_mode) {
+		ret = 0;
+		goto out;
+	}
 
 	drm_mode_set_name(mhdp_state->current_mode);