io_uring: fix races with file table unregister

[ Upstream commit b0380bf ] Fixed file table quiesce might unlock ->uring_lock, potentially letting new requests to be submitted, don't allow those requests to use the table as they will race with unregistration. Reported-and-tested-by: van fantasy <[email protected]> Fixes: 05f3fb3 ("io_uring: avoid ring quiesce for fixed file set unregister and update") Signed-off-by: Pavel Begunkov <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
ADVANTECH-Corp · Jun 22, 2022 · b1e7cad · b1e7cad
1 parent d460a8a
commit b1e7cad
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/fs/io_uring.c b/fs/io_uring.c
@@ -7933,11 +7933,19 @@ static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
 
 static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
 {
+	unsigned nr = ctx->nr_user_files;
 	int ret;
 
 	if (!ctx->file_data)
 		return -ENXIO;
+
+	/*
+	 * Quiesce may unlock ->uring_lock, and while it's not held
+	 * prevent new requests using the table.
+	 */
+	ctx->nr_user_files = 0;
 	ret = io_rsrc_ref_quiesce(ctx->file_data, ctx);
+	ctx->nr_user_files = nr;
 	if (!ret)
 		__io_sqe_files_unregister(ctx);
 	return ret;