[PATCH 6.12 181/218] io_uring: fix potential page leak in io_sqe_buffer_register()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.12-stable review patch.  If anyone has any objections, please let me know.

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

From: Penglei Jiang <superman.xpt@gmail.com>

Commit e1c75831f682eef0f68b35723437146ed86070b1 upstream.

If allocation of the 'imu' fails, then the existing pages aren't
unpinned in the error path. This is mostly a theoretical issue,
requiring fault injection to hit.

Move unpin_user_pages() to unified error handling to fix the page leak
issue.

Fixes: d8c2237d0aa9 ("io_uring: add io_pin_pages() helper")
Signed-off-by: Penglei Jiang <superman.xpt@gmail.com>
Link: https://lore.kernel.org/r/20250617165644.79165-1-superman.xpt@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 io_uring/rsrc.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -983,10 +983,8 @@ static int io_sqe_buffer_register(struct
 		goto done;
 
 	ret = io_buffer_account_pin(ctx, pages, nr_pages, imu, last_hpage);
-	if (ret) {
-		unpin_user_pages(pages, nr_pages);
+	if (ret)
 		goto done;
-	}
 
 	size = iov->iov_len;
 	/* store original address for later verification */
@@ -1010,8 +1008,11 @@ static int io_sqe_buffer_register(struct
 		size -= vec_len;
 	}
 done:
-	if (ret)
+	if (ret) {
 		kvfree(imu);
+		if (pages)
+			unpin_user_pages(pages, nr_pages);
+	}
 	kvfree(pages);
 	return ret;
 }