Am 2022-03-17 um 09:16 schrieb Lee Jones:
Presently the Client can be freed whilst still in use.
Use the already provided lock to prevent this.
Cc: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: "Christian König" <christian.koenig@xxxxxxx>
Cc: "Pan, Xinhui" <Xinhui.Pan@xxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: amd-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
---
drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
index e4beebb1c80a2..3b9ac1e87231f 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
@@ -145,8 +145,11 @@ static int kfd_smi_ev_release(struct inode *inode, struct file *filep)
spin_unlock(&dev->smi_lock);
synchronize_rcu();
+
+ spin_lock(&client->lock);
kfifo_free(&client->fifo);
kfree(client);
+ spin_unlock(&client->lock);
The spin_unlock is after the spinlock data structure has been freed.
There should be no concurrent users here, since we are freeing the data
structure. If there still are concurrent users at this point, they will
crash anyway. So the locking is unnecessary.
return 0;
}
@@ -247,11 +250,13 @@ int kfd_smi_event_open(struct kfd_dev *dev, uint32_t *fd)
return ret;
}
+ spin_lock(&client->lock);
The client was just allocated, and it wasn't added to the client list or
given to user mode yet. So there can be no concurrent users at this
point. The locking is unnecessary.
There could be potential issues if someone uses the file descriptor by
dumb luck before this function returns. So maybe we need to move the
anon_inode_getfd to the end of the function (just before list_add_rcu)
so that we only create the file descriptor after the client structure is
fully initialized.
Regards,
Felix
ret = anon_inode_getfd(kfd_smi_name, &kfd_smi_ev_fops, (void *)client,
O_RDWR);
if (ret < 0) {
kfifo_free(&client->fifo);
kfree(client);
+ spin_unlock(&client->lock);
return ret;
}
*fd = ret;
@@ -264,6 +269,7 @@ int kfd_smi_event_open(struct kfd_dev *dev, uint32_t *fd)
spin_lock(&dev->smi_lock);
list_add_rcu(&client->list, &dev->smi_clients);
spin_unlock(&dev->smi_lock);
+ spin_unlock(&client->lock);
return 0;
}
