perf/core: Don't leak AUX buffer refcount on allocation failure

Failure of the AUX buffer allocation leaks the reference count.

Set the reference count to 1 only when the allocation succeeds.

Fixes: 45bfb2e ("perf: Add AUX area to ring buffer for raw data streams")
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Lorenzo Stoakes <[email protected]>
Cc: [email protected]

Author: KAGA-KOKO

kernel/events/core.c

@@ -7051,8 +7051,6 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 			ret = 0;
 			goto unlock;
 		}
-
-		atomic_set(&rb->aux_mmap_count, 1);
 	}
 
 	user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);
@@ -7119,8 +7117,10 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 	} else {
 		ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages,
 				   event->attr.aux_watermark, flags);
-		if (!ret)
+		if (!ret) {
+			atomic_set(&rb->aux_mmap_count, 1);
 			rb->aux_mmap_locked = extra;
+		}
 	}
 
 unlock:
@@ -7130,6 +7130,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 
 		atomic_inc(&event->mmap_count);
 	} else if (rb) {
+		/* AUX allocation failed */
 		atomic_dec(&rb->mmap_count);
 	}
 aux_unlock: