Re: [PATCH 03/11] drm/v3d: Fix potential memory leak in the performance extension

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On 7/11/24 06:15, Tvrtko Ursulin wrote:
From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>

If fetching of userspace memory fails during the main loop, all drm sync
objs looked up until that point will be leaked because of the missing
drm_syncobj_put.

Fix it by exporting and using a common cleanup helper.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>
Fixes: bae7cb5d6800 ("drm/v3d: Create a CPU job extension for the reset performance query job")
Cc: Maíra Canal <mcanal@xxxxxxxxxx>
Cc: Iago Toral Quiroga <itoral@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v6.8+
---
  drivers/gpu/drm/v3d/v3d_drv.h    |  2 ++
  drivers/gpu/drm/v3d/v3d_sched.c  | 22 ++++++++++----
  drivers/gpu/drm/v3d/v3d_submit.c | 50 ++++++++++++++++++++------------
  3 files changed, 49 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
index e208ffdfba32..dd3ead4cb8bd 100644
--- a/drivers/gpu/drm/v3d/v3d_drv.h
+++ b/drivers/gpu/drm/v3d/v3d_drv.h
@@ -565,6 +565,8 @@ void v3d_mmu_remove_ptes(struct v3d_bo *bo);
  /* v3d_sched.c */
  void v3d_timestamp_query_info_free(struct v3d_timestamp_query_info *query_info,
  				   unsigned int count);
+void v3d_performance_query_info_free(struct v3d_performance_query_info *query_info,
+				     unsigned int count);
  void v3d_job_update_stats(struct v3d_job *job, enum v3d_queue queue);
  int v3d_sched_init(struct v3d_dev *v3d);
  void v3d_sched_fini(struct v3d_dev *v3d);
diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
index 59dc0287dab9..5fbbee47c6b7 100644
--- a/drivers/gpu/drm/v3d/v3d_sched.c
+++ b/drivers/gpu/drm/v3d/v3d_sched.c
@@ -87,20 +87,30 @@ v3d_timestamp_query_info_free(struct v3d_timestamp_query_info *query_info,
  	}
  }
+void
+v3d_performance_query_info_free(struct v3d_performance_query_info *query_info,
+				unsigned int count)
+{
+	if (query_info->queries) {
+		unsigned int i;
+
+		for (i = 0; i < count; i++)
+			drm_syncobj_put(query_info->queries[i].syncobj);
+
+		kvfree(query_info->queries);
+	}
+}
+
  static void
  v3d_cpu_job_free(struct drm_sched_job *sched_job)
  {
  	struct v3d_cpu_job *job = to_cpu_job(sched_job);
-	struct v3d_performance_query_info *performance_query = &job->performance_query;
v3d_timestamp_query_info_free(&job->timestamp_query,
  				      job->timestamp_query.count);
- if (performance_query->queries) {
-		for (int i = 0; i < performance_query->count; i++)
-			drm_syncobj_put(performance_query->queries[i].syncobj);
-		kvfree(performance_query->queries);
-	}
+	v3d_performance_query_info_free(&job->performance_query,
+					job->performance_query.count);
v3d_job_cleanup(&job->base);
  }
diff --git a/drivers/gpu/drm/v3d/v3d_submit.c b/drivers/gpu/drm/v3d/v3d_submit.c
index 121bf1314b80..d626c8539b04 100644
--- a/drivers/gpu/drm/v3d/v3d_submit.c
+++ b/drivers/gpu/drm/v3d/v3d_submit.c
@@ -640,6 +640,8 @@ v3d_get_cpu_reset_performance_params(struct drm_file *file_priv,
  	u32 __user *syncs;
  	u64 __user *kperfmon_ids;
  	struct drm_v3d_reset_performance_query reset;
+	unsigned int i, j;
+	int err;
if (!job) {
  		DRM_DEBUG("CPU job extension was attached to a GPU job.\n");
@@ -668,39 +670,43 @@ v3d_get_cpu_reset_performance_params(struct drm_file *file_priv,
  	syncs = u64_to_user_ptr(reset.syncs);
  	kperfmon_ids = u64_to_user_ptr(reset.kperfmon_ids);
- for (int i = 0; i < reset.count; i++) {
+	for (i = 0; i < reset.count; i++) {
  		u32 sync;
  		u64 ids;
  		u32 __user *ids_pointer;
  		u32 id;
if (copy_from_user(&sync, syncs++, sizeof(sync))) {
-			kvfree(job->performance_query.queries);
-			return -EFAULT;
+			err = -EFAULT;
+			goto error;
  		}
- job->performance_query.queries[i].syncobj = drm_syncobj_find(file_priv, sync);
-
  		if (copy_from_user(&ids, kperfmon_ids++, sizeof(ids))) {
-			kvfree(job->performance_query.queries);
-			return -EFAULT;
+			err = -EFAULT;
+			goto error;
  		}
ids_pointer = u64_to_user_ptr(ids); - for (int j = 0; j < reset.nperfmons; j++) {
+		for (j = 0; j < reset.nperfmons; j++) {
  			if (copy_from_user(&id, ids_pointer++, sizeof(id))) {
-				kvfree(job->performance_query.queries);
-				return -EFAULT;
+				err = -EFAULT;
+				goto error;
  			}
job->performance_query.queries[i].kperfmon_ids[j] = id;
  		}
+
+		job->performance_query.queries[i].syncobj = drm_syncobj_find(file_priv, sync);
  	}
  	job->performance_query.count = reset.count;
  	job->performance_query.nperfmons = reset.nperfmons;
return 0;
+
+error:
+	v3d_performance_query_info_free(&job->performance_query, i);
+	return err;
  }
static int
@@ -711,6 +717,8 @@ v3d_get_cpu_copy_performance_query_params(struct drm_file *file_priv,
  	u32 __user *syncs;
  	u64 __user *kperfmon_ids;
  	struct drm_v3d_copy_performance_query copy;
+	unsigned int i, j;
+	int err;
if (!job) {
  		DRM_DEBUG("CPU job extension was attached to a GPU job.\n");
@@ -749,27 +757,27 @@ v3d_get_cpu_copy_performance_query_params(struct drm_file *file_priv,
  		u32 id;
if (copy_from_user(&sync, syncs++, sizeof(sync))) {
-			kvfree(job->performance_query.queries);
-			return -EFAULT;
+			err = -EFAULT;
+			goto error;
  		}
- job->performance_query.queries[i].syncobj = drm_syncobj_find(file_priv, sync);
-
  		if (copy_from_user(&ids, kperfmon_ids++, sizeof(ids))) {
-			kvfree(job->performance_query.queries);
-			return -EFAULT;
+			err = -EFAULT;
+			goto error;
  		}
ids_pointer = u64_to_user_ptr(ids); - for (int j = 0; j < copy.nperfmons; j++) {
+		for (j = 0; j < copy.nperfmons; j++) {
  			if (copy_from_user(&id, ids_pointer++, sizeof(id))) {
-				kvfree(job->performance_query.queries);
-				return -EFAULT;
+				err = -EFAULT;
+				goto error;
  			}
job->performance_query.queries[i].kperfmon_ids[j] = id;
  		}
+
+		job->performance_query.queries[i].syncobj = drm_syncobj_find(file_priv, sync);
  	}
  	job->performance_query.count = copy.count;
  	job->performance_query.nperfmons = copy.nperfmons;
@@ -782,6 +790,10 @@ v3d_get_cpu_copy_performance_query_params(struct drm_file *file_priv,
  	job->copy.stride = copy.stride;
return 0;
+
+error:
+	v3d_performance_query_info_free(&job->performance_query, i);

I'm seeing this compiling warning from this patch:

drivers/gpu/drm/v3d/v3d_submit.c:860:59: warning: variable 'i' is uninitialized when used here [-Wuninitialized] 860 | v3d_performance_query_info_free(&job->performance_query, i);
      |                                                                  ^
drivers/gpu/drm/v3d/v3d_submit.c:781:16: note: initialize the variable 'i' to silence this warning
  781 |         unsigned int i, j;
      |                       ^
      |                        = 0
1 warning generated.

I believe that we are currently defining int i twice.

Best Regards,
- Maíra

+	return err;
  }
/* Whenever userspace sets ioctl extensions, v3d_get_extensions parses data




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