Re: [PATCH] io_uring: Fix NULL dereference in error in io_sqe_files_register()

Pavel Begunkov
2021-02-01T18:39:03Z

On 01/02/2021 12:23, Dan Carpenter wrote:
> If we hit a "goto out_free;" before the "ctx->file_data" pointer has
> been assigned then it leads to a NULL derefence when we call:
>
> free_fixed_rsrc_data(ctx->file_data);
>
> We can fix this by moving the assignment earlier.

looks good, thanks

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>

>
> Fixes: 3cfb739c561e ("io_uring: create common fixed_rsrc_data allocation routines")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> fs/io_uring.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 03748faa5295..8e8b74dd7d9b 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -7869,6 +7869,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
> file_data = alloc_fixed_rsrc_data(ctx);
> if (!file_data)
> return -ENOMEM;
> + ctx->file_data = file_data;
>
> nr_tables = DIV_ROUND_UP(nr_args, IORING_MAX_FILES_TABLE);
> file_data->table = kcalloc(nr_tables, sizeof(*file_data->table),
> @@ -7878,7 +7879,6 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
>
> if (io_sqe_alloc_file_tables(file_data, nr_tables, nr_args))
> goto out_free;
> - ctx->file_data = file_data;
>
> for (i = 0; i < nr_args; i++, ctx->nr_user_files++) {
> struct fixed_rsrc_table *table;
>

--
Pavel Begunkov