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authorWei Wang <weiwan@google.com>2017-10-23 14:59:35 -0700
committerDavid S. Miller <davem@davemloft.net>2017-10-24 18:51:26 +0900
commit87b1af8dcc084d3d509d55067185ca74aed70ce2 (patch)
tree93f5dc5858356ebc0c0d3c7db47a97e4a7506e73 /net/ipv6
parent71c02379c762cb616c00fd5c4ed253fbf6bbe11b (diff)
ipv6: add ip6_null_entry check in rt6_select()
In rt6_select(), fn->leaf could be pointing to net->ipv6.ip6_null_entry. In this case, we should directly return instead of trying to carry on with the rest of the process. If not, we could crash at: spin_lock_bh(&leaf->rt6i_table->rt6_lock); because net->ipv6.ip6_null_entry does not have rt6i_table set. Syzkaller recently reported following issue on net-next: Use struct sctp_sack_info instead kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: sctp: [Deprecated]: syz-executor4 (pid 26496) Use of struct sctp_assoc_value in delayed_ack socket option. Use struct sctp_sack_info instead CPU: 1 PID: 26523 Comm: syz-executor6 Not tainted 4.14.0-rc4+ #85 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801d147e3c0 task.stack: ffff8801a4328000 RIP: 0010:debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline] RIP: 0010:do_raw_spin_lock+0x23/0x1e0 kernel/locking/spinlock_debug.c:112 RSP: 0018:ffff8801a432ed70 EFLAGS: 00010207 RAX: dffffc0000000000 RBX: 0000000000000018 RCX: 0000000000000000 RDX: 0000000000000003 RSI: 0000000000000000 RDI: 000000000000001c RBP: ffff8801a432ed90 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8482b279 R12: ffff8801ce2ff3a0 sctp: [Deprecated]: syz-executor1 (pid 26546) Use of int in maxseg socket option. Use struct sctp_assoc_value instead R13: dffffc0000000000 R14: ffff8801d971e000 R15: ffff8801ce2ff0d8 FS: 00007f56e82f5700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001ddbc22000 CR3: 00000001a4a04000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock_bh include/linux/spinlock_api_smp.h:136 [inline] _raw_spin_lock_bh+0x39/0x40 kernel/locking/spinlock.c:175 spin_lock_bh include/linux/spinlock.h:321 [inline] rt6_select net/ipv6/route.c:786 [inline] ip6_pol_route+0x1be3/0x3bd0 net/ipv6/route.c:1650 sctp: [Deprecated]: syz-executor1 (pid 26576) Use of int in maxseg socket option. Use struct sctp_assoc_value instead TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters. ip6_pol_route_output+0x4c/0x60 net/ipv6/route.c:1843 fib6_rule_lookup+0x9e/0x2a0 net/ipv6/ip6_fib.c:309 ip6_route_output_flags+0x1f1/0x2b0 net/ipv6/route.c:1871 ip6_route_output include/net/ip6_route.h:80 [inline] ip6_dst_lookup_tail+0x4ea/0x970 net/ipv6/ip6_output.c:953 ip6_dst_lookup_flow+0xc8/0x270 net/ipv6/ip6_output.c:1076 sctp_v6_get_dst+0x675/0x1c30 net/sctp/ipv6.c:274 sctp_transport_route+0xa8/0x430 net/sctp/transport.c:287 sctp_assoc_add_peer+0x4fe/0x1100 net/sctp/associola.c:656 __sctp_connect+0x251/0xc80 net/sctp/socket.c:1187 sctp_connect+0xb4/0xf0 net/sctp/socket.c:4209 inet_dgram_connect+0x16b/0x1f0 net/ipv4/af_inet.c:541 SYSC_connect+0x20a/0x480 net/socket.c:1642 SyS_connect+0x24/0x30 net/socket.c:1623 entry_SYSCALL_64_fastpath+0x1f/0xbe Fixes: 66f5d6ce53e6 ("ipv6: replace rwlock with rcu and spinlock in fib6_table") Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/route.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 46c59a53c53f..605e5dc1c010 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -752,7 +752,7 @@ static struct rt6_info *rt6_select(struct net *net, struct fib6_node *fn,
bool do_rr = false;
int key_plen;
- if (!leaf)
+ if (!leaf || leaf == net->ipv6.ip6_null_entry)
return net->ipv6.ip6_null_entry;
rt0 = rcu_dereference(fn->rr_ptr);