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

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On 11/07/2024 14:00, Maíra Canal wrote:
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.

Yep.. more re-ordering/rebasing fails on my end. Fixed locally.

Regards,

Tvrtko




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