[PATCH 5.4 07/67] io_uring: Fix use-after-free in io_sq_wq_submit_work()

Greg Kroah-Hartman
2020-08-10T15:27:16Z

From: Guoyu Huang <hgy5945@gmail.com>

when ctx->sqo_mm is zero, io_sq_wq_submit_work() frees 'req'
without deleting it from 'task_list'. After that, 'req' is
accessed in io_ring_ctx_wait_and_kill() which lead to
a use-after-free.

Signed-off-by: Guoyu Huang <hgy5945@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/io_uring.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2232,6 +2232,7 @@ restart:
if (io_req_needs_user(req) && !cur_mm) {
if (!mmget_not_zero(ctx->sqo_mm)) {
ret = -EFAULT;
+ goto end_req;
} else {
cur_mm = ctx->sqo_mm;
use_mm(cur_mm);