linux-kernel - [PATCH] drm/radeon:avoid null pointer dereference when dev is not bound

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Message-Id: <1609057469-3844200-1-git-send-email-bodefang@126.com>
Date:   Sun, 27 Dec 2020 16:24:29 +0800
From:   Defang Bo <bodefang@....com>
To:     airlied@...ux.ie, daniel@...ll.ch
Cc:     alexander.deucher@....com, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Defang Bo <bodefang@....com>
Subject: [PATCH] drm/radeon:avoid null pointer dereference when dev is not bound

[Why]
Similar to commit<0fa375e6>. If the set_state/can_switch code access the drm_device when dev is not bound,
a null pointer dereference can happen.

[How]
Add sanity checks to prevent it.

Signed-off-by: Defang Bo <bodefang@....com>
---
 drivers/gpu/drm/radeon/radeon_device.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 266e3cb..50a1a60 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1224,6 +1224,9 @@ static void radeon_switcheroo_set_state(struct pci_dev *pdev, enum vga_switchero
 {
 	struct drm_device *dev = pci_get_drvdata(pdev);
 
+	if (!dev)
+		return;
+
 	if (radeon_is_px(dev) && state == VGA_SWITCHEROO_OFF)
 		return;
 
@@ -1257,6 +1260,9 @@ static void radeon_switcheroo_set_state(struct pci_dev *pdev, enum vga_switchero
 static bool radeon_switcheroo_can_switch(struct pci_dev *pdev)
 {
 	struct drm_device *dev = pci_get_drvdata(pdev);
+
+	if (!dev)
+		return false;
 
 	/*
 	 * FIXME: open_count is protected by drm_global_mutex but that would lead to
-- 
2.7.4