From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Thomas Gleixner <tglx@linutronix.de>,
	Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: [PATCH 6.1 233/253] perf/core: Dont leak AUX buffer refcount on allocation failure
Date: Tue, 12 Aug 2025 19:30:21 +0200
Message-ID: <20250812172958.743385730@linuxfoundation.org>
In-Reply-To: <20250812172948.675299901@linuxfoundation.org>
References: <20250812172948.675299901@linuxfoundation.org>
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6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Gleixner <tglx@linutronix.de>

commit 5468c0fbccbb9d156522c50832244a8b722374fb upstream.

Failure of the AUX buffer allocation leaks the reference count.

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

Fixes: 45bfb2e50471 ("perf/core: Add AUX area to ring buffer for raw data streams")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/events/core.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6381,9 +6381,7 @@ static int perf_mmap(struct file *file,
 			goto unlock;
 		}
 
-		atomic_set(&rb->aux_mmap_count, 1);
 		user_extra = nr_pages;
-
 		goto accounting;
 	}
 
@@ -6485,8 +6483,10 @@ accounting:
 	} 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:
@@ -6496,6 +6496,7 @@ unlock:
 
 		atomic_inc(&event->mmap_count);
 	} else if (rb) {
+		/* AUX allocation failed */
 		atomic_dec(&rb->mmap_count);
 	}
 aux_unlock: