6.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
commit f4a1254f2a076afb0edd473589bf40f9b4d36b41 upstream.
Only the current owner of a request is allowed to write into req->flags.
Hence, the cancellation path should never touch it. Add a new field
instead of the flag, move it into the 3rd cache line because it should
always be initialised. poll_refs can move further as polling is an
involved process anyway.
It's a minimal patch, in the future we can and should find a better
place for it and remove now unused REQ_F_CANCEL_SEQ.
Fixes: 521223d7c229f ("io_uring/cancel: don't default to setting req->work.cancel_seq")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Li Shi <sl1589472800@xxxxxxxxx>
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Link: https://lore.kernel.org/r/6827b129f8f0ad76fa9d1f0a773de938b240ffab.1718323430.git.asml.silence@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/io_uring_types.h | 3 ++-
io_uring/cancel.h | 4 ++--
io_uring/io_uring.c | 1 +
3 files changed, 5 insertions(+), 3 deletions(-)
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -653,7 +653,7 @@ struct io_kiocb {
struct io_rsrc_node *rsrc_node;
atomic_t refs;
- atomic_t poll_refs;
+ bool cancel_seq_set;
struct io_task_work io_task_work;
/* for polled requests, i.e. IORING_OP_POLL_ADD and async armed poll */
struct hlist_node hash_node;
@@ -662,6 +662,7 @@ struct io_kiocb {
/* opcode allocated if it needs to store data for async defer */
void *async_data;
/* linked requests, IFF REQ_F_HARDLINK or REQ_F_LINK are set */
+ atomic_t poll_refs;
struct io_kiocb *link;
/* custom credentials, valid IFF REQ_F_CREDS is set */
const struct cred *creds;
--- a/io_uring/cancel.h
+++ b/io_uring/cancel.h
@@ -27,10 +27,10 @@ bool io_cancel_req_match(struct io_kiocb
static inline bool io_cancel_match_sequence(struct io_kiocb *req, int sequence)
{
- if ((req->flags & REQ_F_CANCEL_SEQ) && sequence == req->work.cancel_seq)
+ if (req->cancel_seq_set && sequence == req->work.cancel_seq)
return true;
- req->flags |= REQ_F_CANCEL_SEQ;
+ req->cancel_seq_set = true;
req->work.cancel_seq = sequence;
return false;
}
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2211,6 +2211,7 @@ static int io_init_req(struct io_ring_ct
req->file = NULL;
req->rsrc_node = NULL;
req->task = current;
+ req->cancel_seq_set = false;
if (unlikely(opcode >= IORING_OP_LAST)) {
req->opcode = 0;
