From: Eric Dumazet <eduma...@google.com>
reqsk_queue_destroy() and reqsk_queue_unlink() should use
del_timer_sync() instead of del_timer() before calling reqsk_put(),
otherwise we could free a req still used by another cpu.
But before doing so, reqsk_queue_destroy() must release syn_wait_lock
spinlock or risk a dead lock, as reqsk_timer_handler() might
need to take this same spinlock from reqsk_queue_unlink() (called from
inet_csk_reqsk_queue_drop())
Fixes: fa76ce7328b2 ("inet: get rid of central tcp/dccp listener timer")
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
net/core/request_sock.c | 8 +++++++-
net/ipv4/inet_connection_sock.c | 2 +-
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/net/core/request_sock.c b/net/core/request_sock.c
index 87b22c0..b42f0e2 100644
--- a/net/core/request_sock.c
+++ b/net/core/request_sock.c
@@ -103,10 +103,16 @@ void reqsk_queue_destroy(struct request_sock_queue *queue)
spin_lock_bh(&queue->syn_wait_lock);
while ((req = lopt->syn_table[i]) != NULL) {
lopt->syn_table[i] = req->dl_next;
+ /* Because of following del_timer_sync(),
+ * we must release the spinlock here
+ * or risk a dead lock.
+ */
+ spin_unlock_bh(&queue->syn_wait_lock);
atomic_inc(&lopt->qlen_dec);
- if (del_timer(&req->rsk_timer))
+ if (del_timer_sync(&req->rsk_timer))
reqsk_put(req);
reqsk_put(req);
+ spin_lock_bh(&queue->syn_wait_lock);
}
spin_unlock_bh(&queue->syn_wait_lock);
}
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 60021d0..05e3145 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -593,7 +593,7 @@ static bool reqsk_queue_unlink(struct request_sock_queue
*queue,
}
spin_unlock(&queue->syn_wait_lock);
- if (del_timer(&req->rsk_timer))
+ if (del_timer_sync(&req->rsk_timer))
reqsk_put(req);
return found;
}
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