This is a note to let you know that I've just added the patch titled
inet: fix potential deadlock in reqsk_queue_unlink()
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-potential-deadlock-in-reqsk_queue_unlink.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 83fccfc3940c4a2db90fd7e7079f5b465cd8c6af Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Thu, 13 Aug 2015 15:44:51 -0700
Subject: inet: fix potential deadlock in reqsk_queue_unlink()
From: Eric Dumazet <edumazet@xxxxxxxxxx>
commit 83fccfc3940c4a2db90fd7e7079f5b465cd8c6af upstream.
When replacing del_timer() with del_timer_sync(), I introduced
a deadlock condition :
reqsk_queue_unlink() is called from inet_csk_reqsk_queue_drop()
inet_csk_reqsk_queue_drop() can be called from many contexts,
one being the timer handler itself (reqsk_timer_handler()).
In this case, del_timer_sync() loops forever.
Simple fix is to test if timer is pending.
Fixes: 2235f2ac75fd ("inet: fix races with reqsk timers")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Holger Hoffstätte <holger.hoffstaette@xxxxxxxxxxxxxx>
Cc: Andre Tomt <andre@xxxxxxxx>
Cc: Chris Caputo <ccaputo@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/inet_connection_sock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 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_sync(&req->rsk_timer))
+ if (timer_pending(&req->rsk_timer) && 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/inet-fix-potential-deadlock-in-reqsk_queue_unlink.patch
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