This is a note to let you know that I've just added the patch titled
net: add pfmemalloc check in sk_add_backlog()
to the 4.2-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:
net-add-pfmemalloc-check-in-sk_add_backlog.patch
and it can be found in the queue-4.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From foo@baz Thu Oct 22 17:25:24 PDT 2015
From: Eric Dumazet <[email protected]>
Date: Tue, 29 Sep 2015 18:52:25 -0700
Subject: net: add pfmemalloc check in sk_add_backlog()
From: Eric Dumazet <[email protected]>
[ Upstream commit c7c49b8fde26b74277188bdc6c9dca38db6fa35b ]
Greg reported crashes hitting the following check in __sk_backlog_rcv()
BUG_ON(!sock_flag(sk, SOCK_MEMALLOC));
The pfmemalloc bit is currently checked in sk_filter().
This works correctly for TCP, because sk_filter() is ran in
tcp_v[46]_rcv() before hitting the prequeue or backlog checks.
For UDP or other protocols, this does not work, because the sk_filter()
is ran from sock_queue_rcv_skb(), which might be called _after_ backlog
queuing if socket is owned by user by the time packet is processed by
softirq handler.
Fixes: b4b9e35585089 ("netvm: set PF_MEMALLOC as appropriate during SKB
processing")
Signed-off-by: Eric Dumazet <[email protected]>
Reported-by: Greg Thelen <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
include/net/sock.h | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -826,6 +826,14 @@ static inline __must_check int sk_add_ba
if (sk_rcvqueues_full(sk, limit))
return -ENOBUFS;
+ /*
+ * If the skb was allocated from pfmemalloc reserves, only
+ * allow SOCK_MEMALLOC sockets to use it as this socket is
+ * helping free memory
+ */
+ if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
+ return -ENOMEM;
+
__sk_add_backlog(sk, skb);
sk->sk_backlog.len += skb->truesize;
return 0;
Patches currently in stable-queue which might be from [email protected] are
queue-4.2/inet-fix-races-in-reqsk_queue_hash_req.patch
queue-4.2/net-add-pfmemalloc-check-in-sk_add_backlog.patch
queue-4.2/inet-fix-race-in-reqsk_queue_unlink.patch
queue-4.2/net-unix-fix-logic-about-sk_peek_offset.patch
queue-4.2/act_mirred-clear-sender-cpu-before-sending-to-tx.patch
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