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

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Message-Id: <1609069604-3949767-1-git-send-email-bodefang@126.com>
Date:   Sun, 27 Dec 2020 19:46:44 +0800
From:   Defang Bo <bodefang@....com>
To:     airlied@...ux.ie, daniel@...ll.ch, sumit.semwal@...aro.org
Cc:     alexander.deucher@....com, christian.koenig@....com,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linaro-mm-sig@...ts.linaro.org, Defang Bo <bodefang@....com>
Subject: [PATCH] drm/amd:avoid null pointer dereference when dev is not bound

[Why]
Similar to commit<0fa375e6>. If amdgpu_switcheroo_can_switch 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/amd/amdgpu/amdgpu_device.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 37da353..f70e528 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -1439,6 +1439,9 @@ static void amdgpu_switcheroo_set_state(struct pci_dev *pdev,
 static bool amdgpu_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