If io_sqe_files_unregister() faults on io_rsrc_ref_quiesce(), it will fail to do unregister leaving files referenced. And that may well happen because of a strayed signal or just because it does allocations inside.

In io_ring_ctx_free() do an unsafe version of unregister, as it's guaranteed to not have requests by that point and so quiesce is useless.

Cc: stable@vger.kernel.org Signed-off-by: Pavel Begunkov asml.silence@gmail.com --- fs/io_uring.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c index 257eddd4cd82..44342ff5c4e1 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7094,6 +7094,10 @@ static void __io_sqe_files_unregister(struct io_ring_ctx *ctx) fput(file); } #endif + io_free_file_tables(&ctx->file_table, ctx->nr_user_files); + kfree(ctx->file_data); + ctx->file_data = NULL; + ctx->nr_user_files = 0; }

static inline void io_rsrc_ref_lock(struct io_ring_ctx *ctx) @@ -7200,21 +7204,14 @@ static struct io_rsrc_data *io_rsrc_data_alloc(struct io_ring_ctx *ctx,

static int io_sqe_files_unregister(struct io_ring_ctx *ctx) { - struct io_rsrc_data *data = ctx->file_data; int ret;

- if (!data) + if (!ctx->file_data) return -ENXIO; - ret = io_rsrc_ref_quiesce(data, ctx); - if (ret) - return ret; - - __io_sqe_files_unregister(ctx); - io_free_file_tables(&ctx->file_table, ctx->nr_user_files); - kfree(data); - ctx->file_data = NULL; - ctx->nr_user_files = 0; - return 0; + ret = io_rsrc_ref_quiesce(ctx->file_data, ctx); + if (!ret) + __io_sqe_files_unregister(ctx); + return ret; }

static void io_sq_thread_unpark(struct io_sq_data *sqd) @@ -7664,7 +7661,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,

ret = io_sqe_files_scm(ctx); if (ret) { - io_sqe_files_unregister(ctx); + __io_sqe_files_unregister(ctx); return ret; }

@@ -8465,7 +8462,11 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx) }

mutex_lock(&ctx->uring_lock); - io_sqe_files_unregister(ctx); + if (ctx->file_data) { + if (!atomic_dec_and_test(&ctx->file_data->refs)) + wait_for_completion(&ctx->file_data->done); + __io_sqe_files_unregister(ctx); + } if (ctx->rings) __io_cqring_overflow_flush(ctx, true); mutex_unlock(&ctx->uring_lock);