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| author | Florian Westphal <fw@strlen.de> | 2017-11-02 16:02:20 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-11-03 14:27:46 +0900 |
| commit | 25dd169aea6553aea548197a5d4580bbdeda1c85 (patch) | |
| tree | 1bf8972a58f3f907274744cf80dd97dec554d4fe /net | |
| parent | e73b49ebd9deeb0ff2cd9ac6fd9c72a433d1e062 (diff) | |
| download | linux-25dd169aea6553aea548197a5d4580bbdeda1c85.tar.gz linux-25dd169aea6553aea548197a5d4580bbdeda1c85.tar.bz2 linux-25dd169aea6553aea548197a5d4580bbdeda1c85.zip | |
fib: fib_dump_info can no longer use __in_dev_get_rtnl
syzbot reported yet another regression added with DOIT_UNLOCKED.
When nexthop is marked as dead, fib_dump_info uses __in_dev_get_rtnl():
./include/linux/inetdevice.h:230 suspicious rcu_dereference_protected() usage!
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz-executor2/23859:
#0: (rcu_read_lock){....}, at: [<ffffffff840283f0>]
inet_rtm_getroute+0xaa0/0x2d70 net/ipv4/route.c:2738
[..]
lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4665
__in_dev_get_rtnl include/linux/inetdevice.h:230 [inline]
fib_dump_info+0x1136/0x13d0 net/ipv4/fib_semantics.c:1377
inet_rtm_getroute+0xf97/0x2d70 net/ipv4/route.c:2785
..
This isn't safe anymore, callers either hold RTNL mutex or rcu read lock,
so these spots must use rcu_dereference_rtnl() or plain rcu_derefence()
(plus unconditional rcu read lock).
This does the latter.
Fixes: 394f51abb3d04f ("ipv4: route: set ipv4 RTM_GETROUTE to not use rtnl")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/fib_semantics.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index 57a5d48acee8..01ed22139ac2 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -1365,8 +1365,6 @@ int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event, nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc)) goto nla_put_failure; if (fi->fib_nhs == 1) { - struct in_device *in_dev; - if (fi->fib_nh->nh_gw && nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw)) goto nla_put_failure; @@ -1374,10 +1372,14 @@ int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event, nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif)) goto nla_put_failure; if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) { - in_dev = __in_dev_get_rtnl(fi->fib_nh->nh_dev); + struct in_device *in_dev; + + rcu_read_lock(); + in_dev = __in_dev_get_rcu(fi->fib_nh->nh_dev); if (in_dev && IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev)) rtm->rtm_flags |= RTNH_F_DEAD; + rcu_read_unlock(); } if (fi->fib_nh->nh_flags & RTNH_F_OFFLOAD) rtm->rtm_flags |= RTNH_F_OFFLOAD; @@ -1400,18 +1402,20 @@ int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event, goto nla_put_failure; for_nexthops(fi) { - struct in_device *in_dev; - rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh)); if (!rtnh) goto nla_put_failure; rtnh->rtnh_flags = nh->nh_flags & 0xFF; if (nh->nh_flags & RTNH_F_LINKDOWN) { - in_dev = __in_dev_get_rtnl(nh->nh_dev); + struct in_device *in_dev; + + rcu_read_lock(); + in_dev = __in_dev_get_rcu(nh->nh_dev); if (in_dev && IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev)) rtnh->rtnh_flags |= RTNH_F_DEAD; + rcu_read_unlock(); } rtnh->rtnh_hops = nh->nh_weight - 1; rtnh->rtnh_ifindex = nh->nh_oif; |