From: Julian Wiedmann jwi@linux.ibm.com
[ Upstream commit 072f79400032f74917726cf76f4248367ea2b5b8 ]
Callbacks for a cmd reply run outside the protection of card->lock, to allow for additional cmds to be issued & enqueued in parallel.
When qeth_send_control_data() bails out for a cmd without having received a reply (eg. due to timeout), its callback may concurrently be processing a reply that just arrived. In this case, the callback potentially accesses a stale reply->reply_param area that eg. was on-stack and has already been released.
To avoid this race, add some locking so that qeth_send_control_data() can (1) wait for a concurrently running callback, and (2) zap any pending callback that still wants to run.
Signed-off-by: Julian Wiedmann jwi@linux.ibm.com Signed-off-by: Jakub Kicinski jakub.kicinski@netronome.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/s390/net/qeth_core.h | 1 + drivers/s390/net/qeth_core_main.c | 20 ++++++++++++++++++++ 2 files changed, 21 insertions(+)
diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h index 784a2e76a1b04..c5f60f95e8db9 100644 --- a/drivers/s390/net/qeth_core.h +++ b/drivers/s390/net/qeth_core.h @@ -640,6 +640,7 @@ struct qeth_seqno { struct qeth_reply { struct list_head list; struct completion received; + spinlock_t lock; int (*callback)(struct qeth_card *, struct qeth_reply *, unsigned long); u32 seqno; diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c index b1823d75dd35c..6b8f99e7d8a81 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -548,6 +548,7 @@ static struct qeth_reply *qeth_alloc_reply(struct qeth_card *card) if (reply) { refcount_set(&reply->refcnt, 1); init_completion(&reply->received); + spin_lock_init(&reply->lock); } return reply; } @@ -832,6 +833,13 @@ static void qeth_issue_next_read_cb(struct qeth_card *card,
if (!reply->callback) { rc = 0; + goto no_callback; + } + + spin_lock_irqsave(&reply->lock, flags); + if (reply->rc) { + /* Bail out when the requestor has already left: */ + rc = reply->rc; } else { if (cmd) { reply->offset = (u16)((char *)cmd - (char *)iob->data); @@ -840,7 +848,9 @@ static void qeth_issue_next_read_cb(struct qeth_card *card, rc = reply->callback(card, reply, (unsigned long)iob); } } + spin_unlock_irqrestore(&reply->lock, flags);
+no_callback: if (rc <= 0) qeth_notify_reply(reply, rc); qeth_put_reply(reply); @@ -1880,6 +1890,16 @@ static int qeth_send_control_data(struct qeth_card *card, int len, rc = (timeout == -ERESTARTSYS) ? -EINTR : -ETIME;
qeth_dequeue_reply(card, reply); + + if (reply_cb) { + /* Wait until the callback for a late reply has completed: */ + spin_lock_irq(&reply->lock); + if (rc) + /* Zap any callback that's still pending: */ + reply->rc = rc; + spin_unlock_irq(&reply->lock); + } + if (!rc) rc = reply->rc; qeth_put_reply(reply);