udp: ipv4: fix an use after free in __udp4_lib_rcv()
Dave Jones reported a use after free in UDP stack : [ 5059.434216] ========================= [ 5059.434314] [ BUG: held lock freed! ] [ 5059.434420] 3.13.0-rc3+ #9 Not tainted [ 5059.434520] ------------------------- [ 5059.434620] named/863 is freeing memory ffff88005e960000-ffff88005e96061f, with a lock still held there! [ 5059.434815] (slock-AF_INET){+.-...}, at: [<ffffffff8149bd21>] udp_queue_rcv_skb+0xd1/0x4b0 [ 5059.435012] 3 locks held by named/863: [ 5059.435086] #0: (rcu_read_lock){.+.+..}, at: [<ffffffff8143054d>] __netif_receive_skb_core+0x11d/0x940 [ 5059.435295] #1: (rcu_read_lock){.+.+..}, at: [<ffffffff81467a5e>] ip_local_deliver_finish+0x3e/0x410 [ 5059.435500] #2: (slock-AF_INET){+.-...}, at: [<ffffffff8149bd21>] udp_queue_rcv_skb+0xd1/0x4b0 [ 5059.435734] stack backtrace: [ 5059.435858] CPU: 0 PID: 863 Comm: named Not tainted 3.13.0-rc3+ #9 [loadavg: 0.21 0.06 0.06 1/115 1365] [ 5059.436052] Hardware name: /D510MO, BIOS MOPNV10J.86A.0175.2010.0308.0620 03/08/2010 [ 5059.436223] 0000000000000002 ffff88007e203ad8 ffffffff8153a372 ffff8800677130e0 [ 5059.436390] ffff88007e203b10 ffffffff8108cafa ffff88005e960000 ffff88007b00cfc0 [ 5059.436554] ffffea00017a5800 ffffffff8141c490 0000000000000246 ffff88007e203b48 [ 5059.436718] Call Trace: [ 5059.436769] <IRQ> [<ffffffff8153a372>] dump_stack+0x4d/0x66 [ 5059.436904] [<ffffffff8108cafa>] debug_check_no_locks_freed+0x15a/0x160 [ 5059.437037] [<ffffffff8141c490>] ? __sk_free+0x110/0x230 [ 5059.437147] [<ffffffff8112da2a>] kmem_cache_free+0x6a/0x150 [ 5059.437260] [<ffffffff8141c490>] __sk_free+0x110/0x230 [ 5059.437364] [<ffffffff8141c5c9>] sk_free+0x19/0x20 [ 5059.437463] [<ffffffff8141cb25>] sock_edemux+0x25/0x40 [ 5059.437567] [<ffffffff8141c181>] sock_queue_rcv_skb+0x81/0x280 [ 5059.437685] [<ffffffff8149bd21>] ? udp_queue_rcv_skb+0xd1/0x4b0 [ 5059.437805] [<ffffffff81499c82>] __udp_queue_rcv_skb+0x42/0x240 [ 5059.437925] [<ffffffff81541d25>] ? _raw_spin_lock+0x65/0x70 [ 5059.438038] [<ffffffff8149bebb>] udp_queue_rcv_skb+0x26b/0x4b0 [ 5059.438155] [<ffffffff8149c712>] __udp4_lib_rcv+0x152/0xb00 [ 5059.438269] [<ffffffff8149d7f5>] udp_rcv+0x15/0x20 [ 5059.438367] [<ffffffff81467b2f>] ip_local_deliver_finish+0x10f/0x410 [ 5059.438492] [<ffffffff81467a5e>] ? ip_local_deliver_finish+0x3e/0x410 [ 5059.438621] [<ffffffff81468653>] ip_local_deliver+0x43/0x80 [ 5059.438733] [<ffffffff81467f70>] ip_rcv_finish+0x140/0x5a0 [ 5059.438843] [<ffffffff81468926>] ip_rcv+0x296/0x3f0 [ 5059.438945] [<ffffffff81430b72>] __netif_receive_skb_core+0x742/0x940 [ 5059.439074] [<ffffffff8143054d>] ? __netif_receive_skb_core+0x11d/0x940 [ 5059.442231] [<ffffffff8108c81d>] ? trace_hardirqs_on+0xd/0x10 [ 5059.442231] [<ffffffff81430d83>] __netif_receive_skb+0x13/0x60 [ 5059.442231] [<ffffffff81431c1e>] netif_receive_skb+0x1e/0x1f0 [ 5059.442231] [<ffffffff814334e0>] napi_gro_receive+0x70/0xa0 [ 5059.442231] [<ffffffffa01de426>] rtl8169_poll+0x166/0x700 [r8169] [ 5059.442231] [<ffffffff81432bc9>] net_rx_action+0x129/0x1e0 [ 5059.442231] [<ffffffff810478cd>] __do_softirq+0xed/0x240 [ 5059.442231] [<ffffffff81047e25>] irq_exit+0x125/0x140 [ 5059.442231] [<ffffffff81004241>] do_IRQ+0x51/0xc0 [ 5059.442231] [<ffffffff81542bef>] common_interrupt+0x6f/0x6f We need to keep a reference on the socket, by using skb_steal_sock() at the right place. Note that another patch is needed to fix a race in udp_sk_rx_dst_set(), as we hold no lock protecting the dst. Fixes: 421b3885 ("udp: ipv4: Add udp early demux") Reported-by: NDave Jones <davej@redhat.com> Signed-off-by: NEric Dumazet <edumazet@google.com> Cc: Shawn Bohrer <sbohrer@rgmadvisors.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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