linux-kernel - [PATCH v2] drm/gma500: Add NULL check for pci_gfx_root in mid_get_vbt

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Message-ID: <20250306112046.17144-1-i.abramov@mt-integration.ru>
Date: Thu, 6 Mar 2025 14:20:45 +0300
From: Ivan Abramov <i.abramov@...integration.ru>
To: Patrik Jakobsson <patrik.r.jakobsson@...il.com>
CC: Ivan Abramov <i.abramov@...integration.ru>, Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>, Alan Cox <alan@...ux.intel.com>, Dave Airlie
	<airlied@...hat.com>, <dri-devel@...ts.freedesktop.org>,
	<linux-kernel@...r.kernel.org>, <lvc-project@...uxtesting.org>
Subject: [PATCH v2] drm/gma500: Add NULL check for pci_gfx_root in mid_get_vbt_data()

Since pci_get_domain_bus_and_slot() can return NULL, add NULL check for
pci_gfx_root in the mid_get_vbt_data().

This change is similar to the checks implemented in mid_get_fuse_settings()
and mid_get_pci_revID(), which were introduced by commit 0cecdd818cd7
("gma500: Final enables for Oaktrail") as "additional minor
bulletproofing".

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: f910b411053f ("gma500: Add the glue to the various BIOS and firmware interfaces")
Signed-off-by: Ivan Abramov <i.abramov@...integration.ru>
---
v2: Update Fixes tag as per Patrik Jakobsson's observation.

 drivers/gpu/drm/gma500/mid_bios.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/gma500/mid_bios.c b/drivers/gpu/drm/gma500/mid_bios.c
index 7e76790c6a81..cba97d7db131 100644
--- a/drivers/gpu/drm/gma500/mid_bios.c
+++ b/drivers/gpu/drm/gma500/mid_bios.c
@@ -279,6 +279,11 @@ static void mid_get_vbt_data(struct drm_psb_private *dev_priv)
 					    0, PCI_DEVFN(2, 0));
 	int ret = -1;
 
+	if (pci_gfx_root == NULL) {
+		WARN_ON(1);
+		return;
+	}
+
 	/* Get the address of the platform config vbt */
 	pci_read_config_dword(pci_gfx_root, 0xFC, &addr);
 	pci_dev_put(pci_gfx_root);
-- 
2.48.1