This is a note to let you know that I've just added the patch titled
inet: fix races with reqsk timers
to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
inet-fix-races-with-reqsk-timers.patch
and it can be found in the queue-4.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Sat Sep 26 11:13:07 PDT 2015
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Mon, 10 Aug 2015 09:09:13 -0700
Subject: inet: fix races with reqsk timers
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 2235f2ac75fd2501c251b0b699a9632e80239a6d ]
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 <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/request_sock.c | 8 +++++++-
net/ipv4/inet_connection_sock.c | 2 +-
2 files changed, 8 insertions(+), 2 deletions(-)
--- a/net/core/request_sock.c
+++ b/net/core/request_sock.c
@@ -103,10 +103,16 @@ void reqsk_queue_destroy(struct request_
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);
}
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -584,7 +584,7 @@ static bool reqsk_queue_unlink(struct re
}
spin_unlock(&queue->syn_wait_lock);
- if (del_timer(&req->rsk_timer))
+ if (del_timer_sync(&req->rsk_timer))
reqsk_put(req);
return found;
}
Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are
queue-4.1/udp-fix-dst-races-with-multicast-early-demux.patch
queue-4.1/fq_codel-fix-a-use-after-free.patch
queue-4.1/inet-fix-possible-request-socket-leak.patch
queue-4.1/ipv6-lock-socket-in-ip6_datagram_connect.patch
queue-4.1/net-fix-skb-csum-races-when-peeking.patch
queue-4.1/inet-fix-races-with-reqsk-timers.patch
queue-4.1/net-graceful-exit-from-netif_alloc_netdev_queues.patch
queue-4.1/bridge-fix-potential-crash-in-__netdev_pick_tx.patch
queue-4.1/inet-frags-fix-defragmented-packet-s-ip-header-for-af_packet.patch
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