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

Dan Carpenter
2021-02-01T12:24:49Z

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.

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;
--
2.29.2