diff options
| author | Wei Wang <weiwan@google.com> | 2018-01-04 01:11:59 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-01-04 22:29:20 +0300 |
| commit | 7bbfe00e025240505db3e04c3b296d7c023b2a26 (patch) | |
| tree | e7668474c0a023eca8e188249f3b9c68013c0e69 | |
| parent | 7d11f77f84b27cef452cee332f4e469503084737 (diff) | |
| download | linux-7bbfe00e025240505db3e04c3b296d7c023b2a26.tar.xz | |
ipv6: fix general protection fault in fib6_add()
In fib6_add(), pn could be NULL if fib6_add_1() failed to return a fib6
node. Checking pn != fn before accessing pn->leaf makes sure pn is not
NULL.
This fixes the following GPF reported by syzkaller:
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 3201 Comm: syzkaller001778 Not tainted 4.15.0-rc5+ #151
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:fib6_add+0x736/0x15a0 net/ipv6/ip6_fib.c:1244
RSP: 0018:ffff8801c7626a70 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000020 RCX: ffffffff84794465
RDX: 0000000000000004 RSI: ffff8801d38935f0 RDI: 0000000000000282
RBP: ffff8801c7626da0 R08: 1ffff10038ec4c35 R09: 0000000000000000
R10: ffff8801c7626c68 R11: 0000000000000000 R12: 00000000fffffffe
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000009
FS: 0000000000000000(0000) GS:ffff8801db200000(0063) knlGS:0000000009b70840
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000020be1000 CR3: 00000001d585a006 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__ip6_ins_rt+0x6c/0x90 net/ipv6/route.c:1006
ip6_route_multipath_add+0xd14/0x16c0 net/ipv6/route.c:3833
inet6_rtm_newroute+0xdc/0x160 net/ipv6/route.c:3957
rtnetlink_rcv_msg+0x733/0x1020 net/core/rtnetlink.c:4411
netlink_rcv_skb+0x21e/0x460 net/netlink/af_netlink.c:2408
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4423
netlink_unicast_kernel net/netlink/af_netlink.c:1275 [inline]
netlink_unicast+0x4e8/0x6f0 net/netlink/af_netlink.c:1301
netlink_sendmsg+0xa4a/0xe60 net/netlink/af_netlink.c:1864
sock_sendmsg_nosec net/socket.c:636 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:646
sock_write_iter+0x31a/0x5d0 net/socket.c:915
call_write_iter include/linux/fs.h:1772 [inline]
do_iter_readv_writev+0x525/0x7f0 fs/read_write.c:653
do_iter_write+0x154/0x540 fs/read_write.c:932
compat_writev+0x225/0x420 fs/read_write.c:1246
do_compat_writev+0x115/0x220 fs/read_write.c:1267
C_SYSC_writev fs/read_write.c:1278 [inline]
compat_SyS_writev+0x26/0x30 fs/read_write.c:1274
do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:125
Reported-by: syzbot <syzkaller@googlegroups.com>
Fixes: 66f5d6ce53e6 ("ipv6: replace rwlock with rcu and spinlock in fib6_table")
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv6/ip6_fib.c | 35 |
1 files changed, 20 insertions, 15 deletions
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index f5285f4e1d08..d11a5578e4f8 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -1241,23 +1241,28 @@ out: * If fib6_add_1 has cleared the old leaf pointer in the * super-tree leaf node we have to find a new one for it. */ - struct rt6_info *pn_leaf = rcu_dereference_protected(pn->leaf, - lockdep_is_held(&table->tb6_lock)); - if (pn != fn && pn_leaf == rt) { - pn_leaf = NULL; - RCU_INIT_POINTER(pn->leaf, NULL); - atomic_dec(&rt->rt6i_ref); - } - if (pn != fn && !pn_leaf && !(pn->fn_flags & RTN_RTINFO)) { - pn_leaf = fib6_find_prefix(info->nl_net, table, pn); -#if RT6_DEBUG >= 2 - if (!pn_leaf) { - WARN_ON(!pn_leaf); - pn_leaf = info->nl_net->ipv6.ip6_null_entry; + if (pn != fn) { + struct rt6_info *pn_leaf = + rcu_dereference_protected(pn->leaf, + lockdep_is_held(&table->tb6_lock)); + if (pn_leaf == rt) { + pn_leaf = NULL; + RCU_INIT_POINTER(pn->leaf, NULL); + atomic_dec(&rt->rt6i_ref); } + if (!pn_leaf && !(pn->fn_flags & RTN_RTINFO)) { + pn_leaf = fib6_find_prefix(info->nl_net, table, + pn); +#if RT6_DEBUG >= 2 + if (!pn_leaf) { + WARN_ON(!pn_leaf); + pn_leaf = + info->nl_net->ipv6.ip6_null_entry; + } #endif - atomic_inc(&pn_leaf->rt6i_ref); - rcu_assign_pointer(pn->leaf, pn_leaf); + atomic_inc(&pn_leaf->rt6i_ref); + rcu_assign_pointer(pn->leaf, pn_leaf); + } } #endif goto failure; |