1. 05 May, 2019 3 commits
    • Eric Dumazet's avatar
      ipv6: fix races in ip6_dst_destroy() · 1a9e0134
      Eric Dumazet authored
      [ Upstream commit 0e233874 ]
      
      We had many syzbot reports that seem to be caused by use-after-free
      of struct fib6_info.
      
      ip6_dst_destroy(), fib6_drop_pcpu_from() and rt6_remove_exception()
      are writers vs rt->from, and use non consistent synchronization among
      themselves.
      
      Switching to xchg() will solve the issues with no possible
      lockdep issues.
      
      BUG: KASAN: user-memory-access in atomic_dec_and_test include/asm-generic/atomic-instrumented.h:747 [inline]
      BUG: KASAN: user-memory-access in fib6_info_release include/net/ip6_fib.h:294 [inline]
      BUG: KASAN: user-memory-access in fib6_info_release include/net/ip6_fib.h:292 [inline]
      BUG: KASAN: user-memory-access in fib6_drop_pcpu_from net/ipv6/ip6_fib.c:927 [inline]
      BUG: KASAN: user-memory-access in fib6_purge_rt+0x4f6/0x670 net/ipv6/ip6_fib.c:960
      Write of size 4 at addr 0000000000ffffb4 by task syz-executor.1/7649
      
      CPU: 0 PID: 7649 Comm: syz-executor.1 Not tainted 5.1.0-rc6+ #183
      Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
      Call Trace:
       __dump_stack lib/dump_stack.c:77 [inline]
       dump_stack+0x172/0x1f0 lib/dump_stack.c:113
       kasan_report.cold+0x5/0x40 mm/kasan/report.c:321
       check_memory_region_inline mm/kasan/generic.c:185 [inline]
       check_memory_region+0x123/0x190 mm/kasan/generic.c:191
       kasan_check_write+0x14/0x20 mm/kasan/common.c:108
       atomic_dec_and_test include/asm-generic/atomic-instrumented.h:747 [inline]
       fib6_info_release include/net/ip6_fib.h:294 [inline]
       fib6_info_release include/net/ip6_fib.h:292 [inline]
       fib6_drop_pcpu_from net/ipv6/ip6_fib.c:927 [inline]
       fib6_purge_rt+0x4f6/0x670 net/ipv6/ip6_fib.c:960
       fib6_del_route net/ipv6/ip6_fib.c:1813 [inline]
       fib6_del+0xac2/0x10a0 net/ipv6/ip6_fib.c:1844
       fib6_clean_node+0x3a8/0x590 net/ipv6/ip6_fib.c:2006
       fib6_walk_continue+0x495/0x900 net/ipv6/ip6_fib.c:1928
       fib6_walk+0x9d/0x100 net/ipv6/ip6_fib.c:1976
       fib6_clean_tree+0xe0/0x120 net/ipv6/ip6_fib.c:2055
       __fib6_clean_all+0x118/0x2a0 net/ipv6/ip6_fib.c:2071
       fib6_clean_all+0x2b/0x40 net/ipv6/ip6_fib.c:2082
       rt6_sync_down_dev+0x134/0x150 net/ipv6/route.c:4057
       rt6_disable_ip+0x27/0x5f0 net/ipv6/route.c:4062
       addrconf_ifdown+0xa2/0x1220 net/ipv6/addrconf.c:3705
       addrconf_notify+0x19a/0x2260 net/ipv6/addrconf.c:3630
       notifier_call_chain+0xc7/0x240 kernel/notifier.c:93
       __raw_notifier_call_chain kernel/notifier.c:394 [inline]
       raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:401
       call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1753
       call_netdevice_notifiers_extack net/core/dev.c:1765 [inline]
       call_netdevice_notifiers net/core/dev.c:1779 [inline]
       dev_close_many+0x33f/0x6f0 net/core/dev.c:1522
       rollback_registered_many+0x43b/0xfd0 net/core/dev.c:8177
       rollback_registered+0x109/0x1d0 net/core/dev.c:8242
       unregister_netdevice_queue net/core/dev.c:9289 [inline]
       unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9282
       unregister_netdevice include/linux/netdevice.h:2658 [inline]
       __tun_detach+0xd5b/0x1000 drivers/net/tun.c:727
       tun_detach drivers/net/tun.c:744 [inline]
       tun_chr_close+0xe0/0x180 drivers/net/tun.c:3443
       __fput+0x2e5/0x8d0 fs/file_table.c:278
       ____fput+0x16/0x20 fs/file_table.c:309
       task_work_run+0x14a/0x1c0 kernel/task_work.c:113
       exit_task_work include/linux/task_work.h:22 [inline]
       do_exit+0x90a/0x2fa0 kernel/exit.c:876
       do_group_exit+0x135/0x370 kernel/exit.c:980
       __do_sys_exit_group kernel/exit.c:991 [inline]
       __se_sys_exit_group kernel/exit.c:989 [inline]
       __x64_sys_exit_group+0x44/0x50 kernel/exit.c:989
       do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe
      RIP: 0033:0x458da9
      Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
      RSP: 002b:00007ffeafc2a6a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
      RAX: ffffffffffffffda RBX: 000000000000001c RCX: 0000000000458da9
      RDX: 0000000000412a80 RSI: 0000000000a54ef0 RDI: 0000000000000043
      RBP: 00000000004be552 R08: 000000000000000c R09: 000000000004c0d1
      R10: 0000000002341940 R11: 0000000000000246 R12: 00000000ffffffff
      R13: 00007ffeafc2a7f0 R14: 000000000004c065 R15: 00007ffeafc2a800
      
      Fixes: a68886a6 ("net/ipv6: Make from in rt6_info rcu protected")
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Reported-by: default avatarsyzbot <syzkaller@googlegroups.com>
      Cc: David Ahern <dsahern@gmail.com>
      Reviewed-by: default avatarDavid Ahern <dsahern@gmail.com>
      Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
      Acked-by: default avatarWei Wang <weiwan@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      1a9e0134
    • Martin KaFai Lau's avatar
      ipv6: A few fixes on dereferencing rt->from · 7ea4f000
      Martin KaFai Lau authored
      [ Upstream commit 886b7a50 ]
      
      It is a followup after the fix in
      commit 9c69a132 ("route: Avoid crash from dereferencing NULL rt->from")
      
      rt6_do_redirect():
      1. NULL checking is needed on rt->from because a parallel
         fib6_info delete could happen that sets rt->from to NULL.
         (e.g. rt6_remove_exception() and fib6_drop_pcpu_from()).
      
      2. fib6_info_hold() is not enough.  Same reason as (1).
         Meaning, holding dst->__refcnt cannot ensure
         rt->from is not NULL or rt->from->fib6_ref is not 0.
      
         Instead of using fib6_info_hold_safe() which ip6_rt_cache_alloc()
         is already doing, this patch chooses to extend the rcu section
         to keep "from" dereference-able after checking for NULL.
      
      inet6_rtm_getroute():
      1. NULL checking is also needed on rt->from for a similar reason.
         Note that inet6_rtm_getroute() is using RTNL_FLAG_DOIT_UNLOCKED.
      
      Fixes: a68886a6 ("net/ipv6: Make from in rt6_info rcu protected")
      Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
      Acked-by: default avatarWei Wang <weiwan@google.com>
      Reviewed-by: default avatarDavid Ahern <dsahern@gmail.com>
      Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      7ea4f000
    • Shmulik Ladkani's avatar
      ipv4: ip_do_fragment: Preserve skb_iif during fragmentation · 3f611a47
      Shmulik Ladkani authored
      [ Upstream commit d2f0c961 ]
      
      Previously, during fragmentation after forwarding, skb->skb_iif isn't
      preserved, i.e. 'ip_copy_metadata' does not copy skb_iif from given
      'from' skb.
      
      As a result, ip_do_fragment's creates fragments with zero skb_iif,
      leading to inconsistent behavior.
      
      Assume for example an eBPF program attached at tc egress (post
      forwarding) that examines __sk_buff->ingress_ifindex:
       - the correct iif is observed if forwarding path does not involve
         fragmentation/refragmentation
       - a bogus iif is observed if forwarding path involves
         fragmentation/refragmentatiom
      
      Fix, by preserving skb_iif during 'ip_copy_metadata'.
      Signed-off-by: default avatarShmulik Ladkani <shmulik.ladkani@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3f611a47
  2. 04 May, 2019 37 commits