user/sven/linux.git/net, branch stable/3.4.y

net: Fix use after free in the recvmmsg exit path

2016-10-26T15:15:47Z

commit 34b88a68f26a75e4fded796f1a49c40f82234b7d upstream. The syzkaller fuzzer hit the following use-after-free: Call Trace: [] __asan_report_load8_noabort+0x3e/0x40 mm/kasan/report.c:295 [] __sys_recvmmsg+0x6fa/0x7f0 net/socket.c:2261 [< inline >] SYSC_recvmmsg net/socket.c:2281 [] SyS_recvmmsg+0x16f/0x180 net/socket.c:2270 [] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 And, as Dmitry rightly assessed, that is because we can drop the reference and then touch it when the underlying recvmsg calls return some packets and then hit an error, which will make recvmmsg to set sock->sk->sk_err, oops, fix it. Reported-and-Tested-by: Dmitry Vyukov Cc: Alexander Potapenko Cc: Eric Dumazet Cc: Kostya Serebryany Cc: Sasha Levin Fixes: a2e2725541fa ("net: Introduce recvmmsg socket syscall") http://lkml.kernel.org/r/20160122211644.GC2470@redhat.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller Signed-off-by: Zefan Li

net/core: revert "net: fix __netdev_update_features return.." and add comment

2016-10-26T15:15:46Z

commit 17b85d29e82cc3c874a497a8bc5764d6a2b043e2 upstream. This reverts commit 00ee59271777 ("net: fix __netdev_update_features return on ndo_set_features failure") and adds a comment explaining why it's okay to return a value other than 0 upon error. Some drivers might actually change flags and return an error so it's better to fire a spurious notification rather than miss these. CC: Michał Mirosław Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller Signed-off-by: Zefan Li

tcp: make challenge acks less predictable

2016-10-26T15:15:44Z

commit 75ff39ccc1bd5d3c455b6822ab09e533c551f758 upstream. Yue Cao claims that current host rate limiting of challenge ACKS (RFC 5961) could leak enough information to allow a patient attacker to hijack TCP sessions. He will soon provide details in an academic paper. This patch increases the default limit from 100 to 1000, and adds some randomization so that the attacker can no longer hijack sessions without spending a considerable amount of probes. Based on initial analysis and patch from Linus. Note that we also have per socket rate limiting, so it is tempting to remove the host limit in the future. v2: randomize the count of challenge acks per second, not the period. Fixes: 282f23c6ee34 ("tcp: implement RFC 5961 3.2") Reported-by: Yue Cao Signed-off-by: Eric Dumazet Suggested-by: Linus Torvalds Cc: Yuchung Cheng Cc: Neal Cardwell Acked-by: Neal Cardwell Acked-by: Yuchung Cheng Signed-off-by: David S. Miller [lizf: Backported to 3.4: - adjust context - use ACCESS_ONCE instead WRITE_ONCE/READ_ONCE - open-code prandom_u32_max()] Signed-off-by: Zefan Li

ipv6: fix handling of blackhole and prohibit routes

2016-10-26T15:15:43Z

commit ef2c7d7b59708d54213c7556a82d14de9a7e4475 upstream. When adding a blackhole or a prohibit route, they were handling like classic routes. Moreover, it was only possible to add this kind of routes by specifying an interface. Bug already reported here: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=498498 Before the patch: $ ip route add blackhole 2001::1/128 RTNETLINK answers: No such device $ ip route add blackhole 2001::1/128 dev eth0 $ ip -6 route | grep 2001 2001::1 dev eth0 metric 1024 After: $ ip route add blackhole 2001::1/128 $ ip -6 route | grep 2001 blackhole 2001::1 dev lo metric 1024 error -22 v2: wrong patch v3: add a field fc_type in struct fib6_config to store RTN_* type Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller Signed-off-by: Zefan Li

ipv6: don't call fib6_run_gc() until routing is ready

2016-10-26T15:15:43Z

commit 2c861cc65ef4604011a0082e4dcdba2819aa191a upstream. When loading the ipv6 module, ndisc_init() is called before ip6_route_init(). As the former registers a handler calling fib6_run_gc(), this opens a window to run the garbage collector before necessary data structures are initialized. If a network device is initialized in this window, adding MAC address to it triggers a NETDEV_CHANGEADDR event, leading to a crash in fib6_clean_all(). Take the event handler registration out of ndisc_init() into a separate function ndisc_late_init() and move it after ip6_route_init(). Signed-off-by: Michal Kubecek Signed-off-by: David S. Miller Signed-off-by: Zefan Li

ipv6: update ip6_rt_last_gc every time GC is run

2016-10-26T15:15:43Z

commit 49a18d86f66d33a20144ecb5a34bba0d1856b260 upstream. As pointed out by Eric Dumazet, net->ipv6.ip6_rt_last_gc should hold the last time garbage collector was run so that we should update it whenever fib6_run_gc() calls fib6_clean_all(), not only if we got there from ip6_dst_gc(). Signed-off-by: Michal Kubecek Signed-off-by: David S. Miller Signed-off-by: Zefan Li

sctp: Prevent soft lockup when sctp_accept() is called during a timeout event

2016-10-26T15:15:43Z

commit 635682a14427d241bab7bbdeebb48a7d7b91638e upstream. A case can occur when sctp_accept() is called by the user during a heartbeat timeout event after the 4-way handshake. Since sctp_assoc_migrate() changes both assoc->base.sk and assoc->ep, the bh_sock_lock in sctp_generate_heartbeat_event() will be taken with the listening socket but released with the new association socket. The result is a deadlock on any future attempts to take the listening socket lock. Note that this race can occur with other SCTP timeouts that take the bh_lock_sock() in the event sctp_accept() is called. BUG: soft lockup - CPU#9 stuck for 67s! [swapper:0] ... RIP: 0010:[] [] _spin_lock+0x1e/0x30 RSP: 0018:ffff880028323b20 EFLAGS: 00000206 RAX: 0000000000000002 RBX: ffff880028323b20 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff880028323be0 RDI: ffff8804632c4b48 RBP: ffffffff8100bb93 R08: 0000000000000000 R09: 0000000000000000 R10: ffff880610662280 R11: 0000000000000100 R12: ffff880028323aa0 R13: ffff8804383c3880 R14: ffff880028323a90 R15: ffffffff81534225 FS: 0000000000000000(0000) GS:ffff880028320000(0000) knlGS:0000000000000000 CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b CR2: 00000000006df528 CR3: 0000000001a85000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process swapper (pid: 0, threadinfo ffff880616b70000, task ffff880616b6cab0) Stack: ffff880028323c40 ffffffffa01c2582 ffff880614cfb020 0000000000000000 0100000000000000 00000014383a6c44 ffff8804383c3880 ffff880614e93c00 ffff880614e93c00 0000000000000000 ffff8804632c4b00 ffff8804383c38b8 Call Trace: [] ? sctp_rcv+0x492/0xa10 [sctp] [] ? nf_iterate+0x69/0xb0 [] ? ip_local_deliver_finish+0x0/0x2d0 [] ? nf_hook_slow+0x76/0x120 [] ? ip_local_deliver_finish+0x0/0x2d0 [] ? ip_local_deliver_finish+0xdd/0x2d0 [] ? ip_local_deliver+0x98/0xa0 [] ? ip_rcv_finish+0x12d/0x440 [] ? ip_rcv+0x275/0x350 [] ? __netif_receive_skb+0x4ab/0x750 ... With lockdep debugging: ===================================== [ BUG: bad unlock balance detected! ] ------------------------------------- CslRx/12087 is trying to release lock (slock-AF_INET) at: [] sctp_generate_timeout_event+0x40/0xe0 [sctp] but there are no more locks to release! other info that might help us debug this: 2 locks held by CslRx/12087: #0: (&asoc->timers[i]){+.-...}, at: [] run_timer_softirq+0x16f/0x3e0 #1: (slock-AF_INET){+.-...}, at: [] sctp_generate_timeout_event+0x23/0xe0 [sctp] Ensure the socket taken is also the same one that is released by saving a copy of the socket before entering the timeout event critical section. Signed-off-by: Karl Heiss Signed-off-by: David S. Miller [bwh: Backported to 3.2: - Net namespaces are not used - Keep using sctp_bh_{,un}lock_sock() - Adjust context] Signed-off-by: Ben Hutchings Signed-off-by: Zefan Li

udp: properly support MSG_PEEK with truncated buffers

2016-10-26T15:15:42Z

commit 197c949e7798fbf28cfadc69d9ca0c2abbf93191 upstream. Backport of this upstream commit into stable kernels : 89c22d8c3b27 ("net: Fix skb csum races when peeking") exposed a bug in udp stack vs MSG_PEEK support, when user provides a buffer smaller than skb payload. In this case, skb_copy_and_csum_datagram_iovec(skb, sizeof(struct udphdr), msg->msg_iov); returns -EFAULT. This bug does not happen in upstream kernels since Al Viro did a great job to replace this into : skb_copy_and_csum_datagram_msg(skb, sizeof(struct udphdr), msg); This variant is safe vs short buffers. For the time being, instead reverting Herbert Xu patch and add back skb->ip_summed invalid changes, simply store the result of udp_lib_checksum_complete() so that we avoid computing the checksum a second time, and avoid the problematic skb_copy_and_csum_datagram_iovec() call. This patch can be applied on recent kernels as it avoids a double checksumming, then backported to stable kernels as a bug fix. Signed-off-by: Eric Dumazet Acked-by: Herbert Xu Signed-off-by: David S. Miller [lizf: Backported to 3.4: adjust context] Signed-off-by: Zefan Li

net: Fix skb csum races when peeking

2016-10-26T15:15:42Z

[ Upstream commit 89c22d8c3b278212eef6a8cc66b570bc840a6f5a ] When we calculate the checksum on the recv path, we store the result in the skb as an optimisation in case we need the checksum again down the line. This is in fact bogus for the MSG_PEEK case as this is done without any locking. So multiple threads can peek and then store the result to the same skb, potentially resulting in bogus skb states. This patch fixes this by only storing the result if the skb is not shared. This preserves the optimisations for the few cases where it can be done safely due to locking or other reasons, e.g., SIOCINQ. Signed-off-by: Herbert Xu Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings Signed-off-by: Zefan Li

af_unix: fix a fatal race with bit fields

2016-10-26T15:15:42Z

commit 60bc851ae59bfe99be6ee89d6bc50008c85ec75d upstream. Using bit fields is dangerous on ppc64/sparc64, as the compiler [1] uses 64bit instructions to manipulate them. If the 64bit word includes any atomic_t or spinlock_t, we can lose critical concurrent changes. This is happening in af_unix, where unix_sk(sk)->gc_candidate/ gc_maybe_cycle/lock share the same 64bit word. This leads to fatal deadlock, as one/several cpus spin forever on a spinlock that will never be available again. A safer way would be to use a long to store flags. This way we are sure compiler/arch wont do bad things. As we own unix_gc_lock spinlock when clearing or setting bits, we can use the non atomic __set_bit()/__clear_bit(). recursion_level can share the same 64bit location with the spinlock, as it is set only with this spinlock held. [1] bug fixed in gcc-4.8.0 : http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52080 Reported-by: Ambrose Feinstein Signed-off-by: Eric Dumazet Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Signed-off-by: David S. Miller Cc: hejianet Signed-off-by: Zefan Li