[PATCH 3.13.y-ckt 48/57] udp: fix dst races with multicast early demux

From	Kamal Mostafa <kamal@canonical.com>
Newsgroups	linux.kernel
Subject	[PATCH 3.13.y-ckt 48/57] udp: fix dst races with multicast early demux
Date	2015-09-22 21:00 +0200
Message-ID	<qbAXf-5tC-1@gated-at.bofh.it> (permalink)
References	<qbzRv-3UF-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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3.13.11-ckt27 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@google.com>

commit 10e2eb878f3ca07ac2f05fa5ca5e6c4c9174a27a upstream.

Multicast dst are not cached. They carry DST_NOCACHE.

As mentioned in commit f8864972126899 ("ipv4: fix dst race in
sk_dst_get()"), these dst need special care before caching them
into a socket.

Caching them is allowed only if their refcnt was not 0, ie we
must use atomic_inc_not_zero()

Also, we must use READ_ONCE() to fetch sk->sk_rx_dst, as mentioned
in commit d0c294c53a771 ("tcp: prevent fetching dst twice in early demux
code")

Fixes: 421b3885bf6d ("udp: ipv4: Add udp early demux")
Tested-by: Gregory Hoggarth <Gregory.Hoggarth@alliedtelesis.co.nz>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Gregory Hoggarth <Gregory.Hoggarth@alliedtelesis.co.nz>
Reported-by: Alex Gartrell <agartrell@fb.com>
Cc: Michal Kubeček <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
[ luis: backported to 3.16: used davem's backport to 3.14 ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 net/ipv4/udp.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b1adb69..78899fa 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1957,12 +1957,19 @@ void udp_v4_early_demux(struct sk_buff *skb)
 
 	skb->sk = sk;
 	skb->destructor = sock_edemux;
-	dst = sk->sk_rx_dst;
+	dst = ACCESS_ONCE(sk->sk_rx_dst);
 
 	if (dst)
 		dst = dst_check(dst, 0);
-	if (dst)
-		skb_dst_set_noref(skb, dst);
+	if (dst) {
+		/* DST_NOCACHE can not be used without taking a reference */
+		if (dst->flags & DST_NOCACHE) {
+			if (likely(atomic_inc_not_zero(&dst->__refcnt)))
+				skb_dst_set(skb, dst);
+		} else {
+			skb_dst_set_noref(skb, dst);
+		}
+	}
 }
 
 int udp_rcv(struct sk_buff *skb)
-- 
1.9.1

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Thread

[3.13.y-ckt stable] Linux 3.13.11-ckt27 stable review Kamal Mostafa <kamal@canonical.com> - 2015-09-22 19:50 +0200
  [PATCH 3.13.y-ckt 15/57] target/iscsi: Fix double free of a TUR followed by a solicited NOPOUT Kamal Mostafa <kamal@canonical.com> - 2015-09-22 19:50 +0200
  [PATCH 3.13.y-ckt 12/57] xen-blkback: replace work_pending with work_busy in purge_persistent_gnt() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 19:50 +0200
  [PATCH 3.13.y-ckt 16/57] rbd: fix copyup completion race Kamal Mostafa <kamal@canonical.com> - 2015-09-22 19:50 +0200
  [PATCH 3.13.y-ckt 57/57] net: gso: use feature flag argument in all protocol gso handlers Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 50/57] ipv6: lock socket in ip6_datagram_connect() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 47/57] rds: fix an integer overflow test in rds_info_getsockopt() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 53/57] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 54/57] net: call rcu_read_lock early in process_backlog Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 52/57] net/tipc: initialize security state for new connection socket Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 40/57] ipc/sem.c: update/correct memory barriers Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 21/57] perf: Fix fasync handling on inherited events Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 51/57] rtnetlink: verify IFLA_VF_INFO attributes before passing them to driver Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 56/57] netlink: don't hold mutex in rcu callback when releasing mmapd ring Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 48/57] udp: fix dst races with multicast early demux Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:00 +0200
  [PATCH 3.13.y-ckt 49/57] sparc64: Fix userspace FPU register corruptions. Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:00 +0200
  [PATCH 3.13.y-ckt 44/57] ip6_gre: release cached dst on tunnel removal Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:00 +0200
  [PATCH 3.13.y-ckt 46/57] net: Fix skb_set_peeked use-after-free bug Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:00 +0200
  [PATCH 3.13.y-ckt 39/57] ipc/sem.c: change memory barrier in sem_lock() to smp_rmb() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 43/57] batman-adv: protect tt_local_entry from concurrent delete events Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 36/57] crypto: caam - fix memory corruption in ahash_final_ctx Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 32/57] libiscsi: Fix host busy blocking during connection teardown Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 24/57] ipc: modify message queue accounting to not take kernel data structures into account Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 42/57] arm64: KVM: Fix host crash when injecting a fault into a 32bit guest Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 35/57] EDAC, ppc4xx: Access mci->csrows array elements properly Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 33/57] libfc: Fix fc_exch_recv_req() error path Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 38/57] ipc,sem: fix use after free on IPC_RMID after a task using same semaphore set exits Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 37/57] mm/hwpoison: fix page refcount of unknown non LRU page Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 25/57] ocfs2: fix BUG in ocfs2_downconvert_thread_do_work() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 17/57] md/raid1: extend spinlock to protect raid1_end_read_request against inconsistencies Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 45/57] net: Fix RCU splat in af_key Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 34/57] libfc: Fix fc_fcp_cleanup_each_cmd() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 41/57] Add factory recertified Crucial M500s to blacklist Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 04/57] virtio-net: drop NETIF_F_FRAGLIST Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 14/57] regmap: regcache-rbtree: Clean new present bits on present bitmap resize Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 27/57] KVM: x86: Use adjustment in guest cycles when handling MSR_IA32_TSC_ADJUST Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 05/57] RDS: verify the underlying transport exists before creating a connection Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 07/57] xen/gntdevt: Fix race condition in gntdev_release() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 13/57] USB: sierra: add 1199:68AB device ID Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 31/57] drm/radeon: add new OLAND pci id Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 10/57] crypto: ixp4xx - Remove bogus BUG_ON on scattered dst buffer Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 29/57] dm thin metadata: delete btrees when releasing metadata snapshot Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 20/57] xhci: fix off by one error in TRB DMA address boundary check Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 30/57] dm btree: add ref counting ops for the leaves of top level btrees Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 18/57] target: REPORT LUNS should return LUN 0 even for dynamic ACLs Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 02/57] md: flush ->event_work before stopping array. Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 03/57] ipv6: addrconf: validate new MTU before applying it Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 22/57] mm, vmscan: Do not wait for page writeback for GFP_NOFS allocations Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 19/57] MIPS: Fix sched_getaffinity with MT FPAFF enabled Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 28/57] localmodconfig: Use Kbuild files too Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 09/57] nfsd: Drop BUG_ON and ignore SECLABEL on absent filesystem Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 11/57] xen-blkfront: don't add indirect pages to list when !feature_persistent Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 08/57] PCI: Restore PCI_MSIX_FLAGS_BIRMASK definition Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 23/57] MIPS: Make set_pte() SMP safe. Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 26/57] fsnotify: fix oops in fsnotify_clear_marks_by_group_flags() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200

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