6.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ming Lei ming.lei@redhat.com
[ Upstream commit 6ee6bd5d4fce502a5b5a2ea805e9ff16e6aa890f ]
Commit 8284066946e6 ("ublk: grab request reference when the request is handled by userspace") doesn't grab request reference in case of recovery reissue. Then the request can be requeued & re-dispatch & failed when canceling uring command.
If it is one zc request, the request can be freed before io_uring returns the zc buffer back, then cause kernel panic:
[ 126.773061] BUG: kernel NULL pointer dereference, address: 00000000000000c8 [ 126.773657] #PF: supervisor read access in kernel mode [ 126.774052] #PF: error_code(0x0000) - not-present page [ 126.774455] PGD 0 P4D 0 [ 126.774698] Oops: Oops: 0000 [#1] SMP NOPTI [ 126.775034] CPU: 13 UID: 0 PID: 1612 Comm: kworker/u64:55 Not tainted 6.14.0_blk+ #182 PREEMPT(full) [ 126.775676] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-1.fc39 04/01/2014 [ 126.776275] Workqueue: iou_exit io_ring_exit_work [ 126.776651] RIP: 0010:ublk_io_release+0x14/0x130 [ublk_drv]
Fixes it by always grabbing request reference for aborting the request.
Reported-by: Caleb Sander Mateos csander@purestorage.com Closes: https://lore.kernel.org/linux-block/CADUfDZodKfOGUeWrnAxcZiLT+puaZX8jDHoj_sf... Fixes: 8284066946e6 ("ublk: grab request reference when the request is handled by userspace") Signed-off-by: Ming Lei ming.lei@redhat.com Link: https://lore.kernel.org/r/20250409011444.2142010-2-ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/block/ublk_drv.c | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-)
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 65badf9ebecf8..9ee1caaa2de07 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1094,6 +1094,25 @@ static void ublk_complete_rq(struct kref *ref) __ublk_complete_rq(req); }
+static void ublk_do_fail_rq(struct request *req) +{ + struct ublk_queue *ubq = req->mq_hctx->driver_data; + + if (ublk_nosrv_should_reissue_outstanding(ubq->dev)) + blk_mq_requeue_request(req, false); + else + __ublk_complete_rq(req); +} + +static void ublk_fail_rq_fn(struct kref *ref) +{ + struct ublk_rq_data *data = container_of(ref, struct ublk_rq_data, + ref); + struct request *req = blk_mq_rq_from_pdu(data); + + ublk_do_fail_rq(req); +} + /* * Since __ublk_rq_task_work always fails requests immediately during * exiting, __ublk_fail_req() is only called from abort context during @@ -1107,10 +1126,13 @@ static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io, { WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
- if (ublk_nosrv_should_reissue_outstanding(ubq->dev)) - blk_mq_requeue_request(req, false); - else - ublk_put_req_ref(ubq, req); + if (ublk_need_req_ref(ubq)) { + struct ublk_rq_data *data = blk_mq_rq_to_pdu(req); + + kref_put(&data->ref, ublk_fail_rq_fn); + } else { + ublk_do_fail_rq(req); + } }
static void ubq_complete_io_cmd(struct ublk_io *io, int res,