[PATCH 10/11] drm/amdkfd: Free queue in procfs_queue_type kobject release callback

[Ian Rogers <irogers@google.com>]

struct queue embeds a struct kobject (q->kobj) for procfs entries, but
procfs_queue_type had no .release callback and uninit_queue() freed q
immediately after kfd_procfs_del_queue() called kobject_put(&q->kobj).
With CONFIG_DEBUG_KOBJECT_RELEASE=y, this causes a use-after-free.

Add kfd_procfs_queue_release() to free struct queue from the kobject
release callback, change kfd_procfs_del_queue() to only remove the
kobject from sysfs via kobject_del(), and drop the final reference in
uninit_queue() via kobject_put().

Fixes: 6d220a7e7971 ("drm/amdkfd: Add queue information to sysfs")
Assisted-by: Antigravity:gemini-3.1-pro
Signed-off-by: Ian Rogers <irogers@google.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 10 ++++++++--
 drivers/gpu/drm/amd/amdkfd/kfd_queue.c   |  5 ++++-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index 0a7c1900da95..6099cb893573 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -510,7 +510,15 @@ static const struct sysfs_ops procfs_queue_ops = {
 	.show = kfd_procfs_queue_show,
 };
 
+static void kfd_procfs_queue_release(struct kobject *kobj)
+{
+	struct queue *q = container_of(kobj, struct queue, kobj);
+
+	kfree(q);
+}
+
 static const struct kobj_type procfs_queue_type = {
+	.release = kfd_procfs_queue_release,
 	.sysfs_ops = &procfs_queue_ops,
 	.default_groups = procfs_queue_groups,
 };
@@ -550,7 +558,6 @@ int kfd_procfs_add_queue(struct queue *q)
 	if (ret < 0) {
 		pr_warn("Creating proc/<pid>/queues/%u failed",
 			q->properties.queue_id);
-		kobject_put(&q->kobj);
 		return ret;
 	}
 
@@ -699,7 +706,6 @@ void kfd_procfs_del_queue(struct queue *q)
 		return;
 
 	kobject_del(&q->kobj);
-	kobject_put(&q->kobj);
 }
 
 int kfd_process_create_wq(void)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_queue.c b/drivers/gpu/drm/amd/amdkfd/kfd_queue.c
index 15eeaaebbbcd..8d1afc5b47e2 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_queue.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_queue.c
@@ -83,7 +83,10 @@ int init_queue(struct queue **q, const struct queue_properties *properties)
 
 void uninit_queue(struct queue *q)
 {
-	kfree(q);
+	if (q && q->kobj.state_initialized)
+		kobject_put(&q->kobj);
+	else
+		kfree(q);
 }
 
 #if IS_ENABLED(CONFIG_HSA_AMD_SVM)
-- 
2.56.0.385.gd3acb90ef8-goog


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