[PATCH] perf: Fix deadlock in perf_mmap()

[Qing Wang <wangqing7171@gmail.com>]

There is a possible deadlock in perf_mmap() if mmap_range() fails then
perf_mmap_close() is called while holding event->mmap_mutex. Since
perf_mmap_close() also acquire the same mutex, this result in self-deadlock.

Fix this by moving the cleanup(perf_mmap_close()) outside the scope of
scoped_guard(mutex, &event->mmap_mutex).

Fixes: 77de62ad3de3 ("perf/core: Fix refcount bug and potential UAF in perf_mmap")
Reported-by: syzbot+196a82fd904572696b3c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=196a82fd904572696b3c
Signed-off-by: Qing Wang <wangqing7171@gmail.com>
---
 kernel/events/core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1f5699b339ec..e5ce03ce926d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7485,9 +7485,12 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 		 */
 		ret = map_range(event->rb, vma);
 		if (ret)
-			perf_mmap_close(vma);
+			goto out_close;
 	}
+	return 0;
 
+out_close:
+	perf_mmap_close(vma);
 	return ret;
 }
 
-- 
2.34.1