[PATCH v2] io_uring: fix filename leak in __io_openat_prep()

[PATCH v2] io_uring: fix filename leak in __io_openat_prep()

[Prithvi Tambewagh]

 __io_openat_prep() allocates a struct filename using getname(). However,
for the condition of the file being installed in the fixed file table as
well as having O_CLOEXEC flag set, the function returns early. At that
point, the request doesn't have REQ_F_NEED_CLEANUP flag set. Due to this,
the memory for the newly allocated struct filename is not cleaned up,
causing a memory leak.

Fix this by setting the REQ_F_NEED_CLEANUP for the request just after the
successful getname() call, so that when the request is torn down, the
filename will be cleaned up, along with other resources needing cleanup.

Reported-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=00e61c43eb5e4740438f
Tested-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Prithvi Tambewagh <activprithvi@gmail.com>
---
 io_uring/openclose.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/io_uring/openclose.c b/io_uring/openclose.c
index bfeb91b31bba..15dde9bd6ff6 100644
--- a/io_uring/openclose.c
+++ b/io_uring/openclose.c
@@ -73,13 +73,13 @@ static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
 		open->filename = NULL;
 		return ret;
 	}
+	req->flags |= REQ_F_NEED_CLEANUP;
 
 	open->file_slot = READ_ONCE(sqe->file_index);
 	if (open->file_slot && (open->how.flags & O_CLOEXEC))
 		return -EINVAL;
 
 	open->nofile = rlimit(RLIMIT_NOFILE);
-	req->flags |= REQ_F_NEED_CLEANUP;
 	if (io_openat_force_async(open))
 		req->flags |= REQ_F_FORCE_ASYNC;
 	return 0;

base-commit: b927546677c876e26eba308550207c2ddf812a43
-- 
2.34.1