linux-kernel - [PATCH][next] drm/amdgpu: fix a dereference on pointer hive before it is null checked

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20200420140846.78062-1-colin.king@canonical.com>
Date:   Mon, 20 Apr 2020 15:08:46 +0100
From:   Colin King <colin.king@...onical.com>
To:     Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        David Zhou <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Felix Kuehling <Felix.Kuehling@....com>,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] drm/amdgpu: fix a dereference on pointer hive before it is null checked

From: Colin Ian King <colin.king@...onical.com>

Currently pointer hive is being dereferenced before it is being null
checked and hence can lead to null pointer dereference issues. Fix this
by only dereferencing pointer hive after it has been null checked.

Addresses-Coverity: ("Dereference before null check")
Fixes: 25d4275e1931 ("drm/amdgpu: fix race between pstate and remote buffer map")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
index 54d8a3e7e75c..2c0a59ba2826 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
@@ -389,15 +389,17 @@ int amdgpu_xgmi_set_pstate(struct amdgpu_device *adev, int pstate)
 {
 	int ret = 0;
 	struct amdgpu_hive_info *hive = amdgpu_get_xgmi_hive(adev, 0);
-	struct amdgpu_device *request_adev = hive->hi_req_gpu ?
-						hive->hi_req_gpu : adev;
+	struct amdgpu_device *request_adev;
 	bool is_hi_req = pstate == AMDGPU_XGMI_PSTATE_MAX_VEGA20;
-	bool init_low = hive->pstate == AMDGPU_XGMI_PSTATE_UNKNOWN;
+	bool init_low;
 
 	/* fw bug so temporarily disable pstate switching */
 	if (!hive || adev->asic_type == CHIP_VEGA20)
 		return 0;
 
+	request_adev = hive->hi_req_gpu ? hive->hi_req_gpu : adev;
+	init_low = hive->pstate == AMDGPU_XGMI_PSTATE_UNKNOWN;
+
 	mutex_lock(&hive->hive_lock);
 
 	if (is_hi_req)
-- 
2.25.1