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From:   Grigory Vasilyev <h0tc0d3@gmail.com>
To:     Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>,
        Melissa Wen <mwen@igalia.com>
Cc:     Grigory Vasilyev <h0tc0d3@gmail.com>,
        Felix Kuehling <Felix.Kuehling@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
        "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, amd-gfx@lists.freedesktop.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: [PATCH] drm/amdkfd: Fix potential NULL pointer dereference
Date:   Tue,  5 Apr 2022 01:21:32 +0300
Message-Id: <20220404222132.12740-1-h0tc0d3@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

In the amdgpu_amdkfd_get_xgmi_bandwidth_mbytes function,
the peer_adev pointer can be NULL and is passed to amdgpu_xgmi_get_num_links.

In amdgpu_xgmi_get_num_links, peer_adev pointer is dereferenced
without any checks: peer_adev->gmc.xgmi.node_id .

Signed-off-by: Grigory Vasilyev <h0tc0d3@gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
index be1a55f8b8c5..1a1006b18016 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
@@ -541,11 +541,10 @@ int amdgpu_amdkfd_get_xgmi_bandwidth_mbytes(struct amdgpu_device *dst,
 	struct amdgpu_device *adev = dst, *peer_adev;
 	int num_links;
 
-	if (adev->asic_type != CHIP_ALDEBARAN)
+	if (!src || adev->asic_type != CHIP_ALDEBARAN)
 		return 0;
 
-	if (src)
-		peer_adev = src;
+	peer_adev = src;
 
 	/* num links returns 0 for indirect peers since indirect route is unknown. */
 	num_links = is_min ? 1 : amdgpu_xgmi_get_num_links(adev, peer_adev);
-- 
2.35.1