io_sqe_files_unregister() uninterruptibly waits for enqueued ref nodes, however requests keeping them may never complete, e.g. because of some userspace dependency. Make sure it's interruptible otherwise it would hang forever.

Cc: stable@vger.kernel.org # 5.6+ Signed-off-by: Pavel Begunkov asml.silence@gmail.com --- fs/io_uring.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c index 6372aba8d0c2..ca46f314640b 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -992,6 +992,10 @@ enum io_mem_account { ACCT_PINNED, };

+static void destroy_fixed_file_ref_node(struct fixed_file_ref_node *ref_node); +static struct fixed_file_ref_node *alloc_fixed_file_ref_node( + struct io_ring_ctx *ctx); + static void __io_complete_rw(struct io_kiocb *req, long res, long res2, struct io_comp_state *cs); static void io_cqring_fill_event(struct io_kiocb *req, long res); @@ -7244,11 +7248,15 @@ static void io_sqe_files_set_node(struct fixed_file_data *file_data, static int io_sqe_files_unregister(struct io_ring_ctx *ctx) { struct fixed_file_data *data = ctx->file_data; - struct fixed_file_ref_node *ref_node = NULL; + struct fixed_file_ref_node *backup_node, *ref_node = NULL; unsigned nr_tables, i; + int ret;

if (!data) return -ENXIO; + backup_node = alloc_fixed_file_ref_node(ctx); + if (!backup_node) + return -ENOMEM;

spin_lock_bh(&data->lock); ref_node = data->node; @@ -7260,7 +7268,18 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx)

/* wait for all refs nodes to complete */ flush_delayed_work(&ctx->file_put_work); - wait_for_completion(&data->done); + do { + ret = wait_for_completion_interruptible(&data->done); + if (!ret) + break; + ret = io_run_task_work_sig(); + if (ret < 0) { + percpu_ref_resurrect(&data->refs); + reinit_completion(&data->done); + io_sqe_files_set_node(data, backup_node); + return ret; + } + } while (1);

__io_sqe_files_unregister(ctx); nr_tables = DIV_ROUND_UP(ctx->nr_user_files, IORING_MAX_FILES_TABLE); @@ -7271,6 +7290,7 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx) kfree(data); ctx->file_data = NULL; ctx->nr_user_files = 0; + destroy_fixed_file_ref_node(backup_node); return 0; }