linux-kernel - [PATCH v2] drm/amdkfd: Fix potential NULL pointer dereferences

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Message-ID: <20180110231509.GA14154@embeddedor.com>
Date:   Wed, 10 Jan 2018 17:15:09 -0600
From:   "Gustavo A. R. Silva" <garsilva@...eddedor.com>
To:     Felix Kuehling <felix.kuehling@....com>,
        Oded Gabbay <oded.gabbay@...il.com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        David Airlie <airlied@...ux.ie>
Cc:     dri-devel@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <garsilva@...eddedor.com>
Subject: [PATCH v2] drm/amdkfd: Fix potential NULL pointer dereferences

In case kfd_get_process_device_data returns null, there are some
null pointer dereferences in functions kfd_bind_processes_to_device
and kfd_unbind_processes_from_device.

Fix this by printing a WARN_ON for PDDs that aren't found and skip
them with continue statements.

Addresses-Coverity-ID: 1463794 ("Dereference null return value")
Addresses-Coverity-ID: 1463772 ("Dereference null return value")
Suggested-by: Felix Kuehling <felix.kuehling@....com>
Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
---
Changes in v2:
 Print a WARN_ON and skip PDDs that aren't found instead of returning
 an error.

 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index a22fb071..4ff5f0f 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -461,7 +461,8 @@ int kfd_bind_processes_to_device(struct kfd_dev *dev)
 	hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {
 		mutex_lock(&p->mutex);
 		pdd = kfd_get_process_device_data(dev, p);
-		if (pdd->bound != PDD_BOUND_SUSPENDED) {
+
+		if (WARN_ON(!pdd) || pdd->bound != PDD_BOUND_SUSPENDED) {
 			mutex_unlock(&p->mutex);
 			continue;
 		}
@@ -501,6 +502,11 @@ void kfd_unbind_processes_from_device(struct kfd_dev *dev)
 		mutex_lock(&p->mutex);
 		pdd = kfd_get_process_device_data(dev, p);
 
+		if (WARN_ON(!pdd)) {
+			mutex_unlock(&p->mutex);
+			continue;
+		}
+
 		if (pdd->bound == PDD_BOUND)
 			pdd->bound = PDD_BOUND_SUSPENDED;
 		mutex_unlock(&p->mutex);
-- 
2.7.4