Hi Felix,

Quoting Felix Kuehling <felix.kuehl...@amd.com>:

Hi Gustavo,

Thanks for catching that. When returning a fault, I think you also need
to srcu_read_unlock(&kfd_processes_srcu, idx).

However, instead of returning an error, I think I'd prefer to skip PDDs
that can't be found with continue statements. That way others would
still suspend and resume successfully. Maybe just print a WARN_ON for
PDDs that aren't found, because that's an unexpected situation,
currently. Maybe in the future it could be normal thing if we ever
support GPU hotplug.


I got it. In that case, what do you think about the following patch instead?

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);


Thank you for the feedback.
--
Gustavo

Regards,
  Felix


On 2018-01-10 11:50 AM, Gustavo A. R. Silva wrote:
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 null checking pdd before dereferencing it.

Addresses-Coverity-ID: 1463794 ("Dereference null return value")
Addresses-Coverity-ID: 1463772 ("Dereference null return value")
Signed-off-by: Gustavo A. R. Silva <garsi...@embeddedor.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index a22fb071..29d51d5 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -461,6 +461,13 @@ 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) {
+                       pr_err("Process device data doesn't exist\n");
+                       mutex_unlock(&p->mutex);
+                       return -EFAULT;
+               }
+
                if (pdd->bound != PDD_BOUND_SUSPENDED) {
                        mutex_unlock(&p->mutex);
                        continue;
@@ -501,6 +508,11 @@ void kfd_unbind_processes_from_device(struct kfd_dev *dev)
                mutex_lock(&p->mutex);
                pdd = kfd_get_process_device_data(dev, p);

+               if (!pdd) {
+                       mutex_unlock(&p->mutex);
+                       return;
+               }
+
                if (pdd->bound == PDD_BOUND)
                        pdd->bound = PDD_BOUND_SUSPENDED;
                mutex_unlock(&p->mutex);






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