6.12-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
[ Upstream commit f2320f1dd6f6f82cb2c7aff23a12bab537bdea89 ]
A recent commit moved the error handling of sqpoll thread and tctx failures into the thread itself, as part of fixing an issue. However, it missed that tctx allocation may also fail, and that io_sq_offload_create() does its own error handling for the task_struct in that case.
Remove the manual task putting in io_sq_offload_create(), as io_sq_thread() will notice that the tctx did not get setup and hence it should put itself and exit.
Reported-by: syzbot+763e12bbf004fb1062e4@syzkaller.appspotmail.com Fixes: ac0b8b327a56 ("io_uring: fix use-after-free of sq->thread in __io_uring_show_fdinfo()") Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- io_uring/sqpoll.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c index 9a63068948957..2faa3058b2d0e 100644 --- a/io_uring/sqpoll.c +++ b/io_uring/sqpoll.c @@ -426,7 +426,6 @@ void io_sqpoll_wait_sq(struct io_ring_ctx *ctx) __cold int io_sq_offload_create(struct io_ring_ctx *ctx, struct io_uring_params *p) { - struct task_struct *task_to_put = NULL; int ret;
/* Retain compatibility with failing for an invalid attach attempt */ @@ -510,7 +509,7 @@ __cold int io_sq_offload_create(struct io_ring_ctx *ctx, rcu_assign_pointer(sqd->thread, tsk); mutex_unlock(&sqd->lock);
- task_to_put = get_task_struct(tsk); + get_task_struct(tsk); ret = io_uring_alloc_task_context(tsk, ctx); wake_up_new_task(tsk); if (ret) @@ -525,8 +524,6 @@ __cold int io_sq_offload_create(struct io_ring_ctx *ctx, complete(&ctx->sq_data->exited); err: io_sq_thread_finish(ctx); - if (task_to_put) - put_task_struct(task_to_put); return ret; }