io_provided_buffer_select() must drop the submit lock, if needed, even
in the error handling case. Failure to do so will leave us with the
ctx->uring_lock held, causing spew like:
====================================
WARNING: iou-wrk-366/368 still has locks held!
5.18.0-rc6-00294-gdf8dc7004331 #994 Not tainted
------------------------------------
1 lock held by iou-wrk-366/368:
#0: ffff0000c72598a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_ring_submit_lock+0x20/0x48
stack backtrace:
CPU: 4 PID: 368 Comm: iou-wrk-366 Not tainted 5.18.0-rc6-00294-gdf8dc7004331 #994
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace.part.0+0xa4/0xd4
show_stack+0x14/0x5c
dump_stack_lvl+0x88/0xb0
dump_stack+0x14/0x2c
debug_check_no_locks_held+0x84/0x90
try_to_freeze.isra.0+0x18/0x44
get_signal+0x94/0x6ec
io_wqe_worker+0x1d8/0x2b4
ret_from_fork+0x10/0x20
and triggering later hangs off get_signal() because we attempt to
re-grab the lock.
Reported-by: syzbot+987d7bb19195ae45208c@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 149c69b04a90 ("io_uring: abstract out provided buffer list selection")
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 3c39f5413c1b..64450af959ff 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3467,20 +3467,23 @@ static void __user *io_provided_buffer_select(struct io_kiocb *req, size_t *len,
struct io_buffer_list *bl,
unsigned int issue_flags)
{
- struct io_buffer *kbuf;
+ void __user *ret = ERR_PTR(-ENOBUFS);
- if (list_empty(&bl->buf_list))
- return ERR_PTR(-ENOBUFS);
+ if (!list_empty(&bl->buf_list)) {
+ struct io_buffer *kbuf;
+
+ kbuf = list_first_entry(&bl->buf_list, struct io_buffer, list);
+ list_del(&kbuf->list);
+ if (*len > kbuf->len)
+ *len = kbuf->len;
+ req->flags |= REQ_F_BUFFER_SELECTED;
+ req->kbuf = kbuf;
+ req->buf_index = kbuf->bid;
+ ret = u64_to_user_ptr(kbuf->addr);
+ }
- kbuf = list_first_entry(&bl->buf_list, struct io_buffer, list);
- list_del(&kbuf->list);
- if (*len > kbuf->len)
- *len = kbuf->len;
- req->flags |= REQ_F_BUFFER_SELECTED;
- req->kbuf = kbuf;
- req->buf_index = kbuf->bid;
io_ring_submit_unlock(req->ctx, issue_flags);
- return u64_to_user_ptr(kbuf->addr);
+ return ret;
}
static void __user *io_buffer_select(struct io_kiocb *req, size_t *len,
--
Jens Axboe
