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charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260626-drm_refcount_wiring-v1-2-cca1a7b3bdef@redhat.com> References: <20260626-drm_refcount_wiring-v1-0-cca1a7b3bdef@redhat.com> In-Reply-To: <20260626-drm_refcount_wiring-v1-0-cca1a7b3bdef@redhat.com> To: Neil Armstrong , Jessica Zhang , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Andrzej Hajda , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Luca Ceresoli , Inki Dae , Jagan Teki , Marek Szyprowski , Laurentiu Palcu , Lucas Stach , Frank Li , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Paul Cercueil , Linus Walleij , Marek Vasut , Stefan Agner , Tomi Valkeinen , Laurent Pinchart , Kieran Bingham , Geert Uytterhoeven , Magnus Damm , Biju Das , Sandy Huang , =?utf-8?q?Heiko_St=C3=BCbner?= , Andy Yan , Yannick Fertre , Raphael Gallais-Pou , Philippe Cornu , Maxime Coquelin , Alexandre Torgue , Chen-Yu Tsai , Samuel Holland , Jyri Sarha , Jingoo Han , Seung-Woo Kim , Kyungmin Park , Krzysztof Kozlowski , Peter Griffin , Alim Akhtar , Alison Wang , Paul Kocialkowski , Alain Volmat , Raphael Gallais-Pou , Thierry Reding , Mikko Perttunen , Jonathan Hunter Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-stm32@st-md-mailman.stormreply.com, linux-sunxi@lists.linux.dev, linux-samsung-soc@vger.kernel.org, linux-tegra@vger.kernel.org, Albert Esteve X-Developer-Signature: v=1; a=ed25519-sha256; t=1782475410; l=2189; i=aesteve@redhat.com; s=20260303; h=from:subject:message-id; bh=k0Fp+8sQr3zfg5u2HHCF4cWKSffOLMXWCbveTegHWXU=; b=KRKEPwGIFR+fYjRsq4WpccAKc6oAuWaZ3suxw8Sgu5kRbJ0u4ST8AVVBZZ+YsbxFZk3NnrCwV M9fcWkBozA3C3IvwVpPUaw76p6L3npppMomWLgUB+8td46HP2LrfqmC X-Developer-Key: i=aesteve@redhat.com; a=ed25519; pk=YSFz6sOHd2L45+Fr8DIvHTi6lSIjhLZ5T+rkxspJt1s= X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 drm_panel_bridge_add_typed() stores a pointer to the drm_panel it wraps, but never acquires a reference to it. If the panel device goes away while a panel_bridge still exists, the dangling pointer can be dereferenced through panel_bridge->panel. Acquire a reference in drm_panel_bridge_add_typed() with drm_panel_get() and release it in each teardown path. Signed-off-by: Albert Esteve --- drivers/gpu/drm/bridge/panel.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c index 4978ec98a0828..6b98ad19508df 100644 --- a/drivers/gpu/drm/bridge/panel.c +++ b/drivers/gpu/drm/bridge/panel.c @@ -294,7 +294,7 @@ struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel, return (void *)panel_bridge; panel_bridge->connector_type = connector_type; - panel_bridge->panel = panel; + panel_bridge->panel = drm_panel_get(panel); panel_bridge->bridge.of_node = panel->dev->of_node; panel_bridge->bridge.ops = DRM_BRIDGE_OP_MODES; @@ -316,6 +316,7 @@ EXPORT_SYMBOL(drm_panel_bridge_add_typed); void drm_panel_bridge_remove(struct drm_bridge *bridge) { struct panel_bridge *panel_bridge; + struct drm_panel *panel; if (!bridge) return; @@ -326,10 +327,12 @@ void drm_panel_bridge_remove(struct drm_bridge *bridge) } panel_bridge = drm_bridge_to_panel_bridge(bridge); + panel = panel_bridge->panel; drm_bridge_remove(bridge); /* TODO remove this after reworking panel_bridge lifetime */ - devm_drm_put_bridge(panel_bridge->panel->dev, bridge); + devm_drm_put_bridge(panel->dev, bridge); + drm_panel_put(panel); } EXPORT_SYMBOL(drm_panel_bridge_remove); @@ -357,11 +360,14 @@ EXPORT_SYMBOL(drm_panel_bridge_set_orientation); static void devm_drm_panel_bridge_release(struct device *dev, void *res) { struct drm_bridge *bridge = *(struct drm_bridge **)res; + struct panel_bridge *panel_bridge; if (!bridge) return; + panel_bridge = drm_bridge_to_panel_bridge(bridge); drm_bridge_remove(bridge); + drm_panel_put(panel_bridge->panel); } /** -- 2.54.0