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Message-Id: <1485147377-11922-1-git-send-email-dsa@cumulusnetworks.com>
Date: Sun, 22 Jan 2017 20:56:17 -0800
From: David Ahern <dsa@...ulusnetworks.com>
To: netdev@...r.kernel.org
Cc: xiaolong.ye@...el.com, David Ahern <dsa@...ulusnetworks.com>
Subject: [PATCH net-next] net: ipv6: ignore null_entry on route dumps
lkp-robot reported a BUG:
[ 10.151226] BUG: unable to handle kernel NULL pointer dereference at 00000198
[ 10.152525] IP: rt6_fill_node+0x164/0x4b8
[ 10.153307] *pdpt = 0000000012ee5001 *pde = 0000000000000000
[ 10.153309]
[ 10.154492] Oops: 0000 [#1]
[ 10.154987] CPU: 0 PID: 909 Comm: netifd Not tainted 4.10.0-rc4-00722-g41e8c70ee162-dirty #10
[ 10.156482] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[ 10.158254] task: d0deb000 task.stack: d0e0c000
[ 10.159059] EIP: rt6_fill_node+0x164/0x4b8
[ 10.159780] EFLAGS: 00010296 CPU: 0
[ 10.160404] EAX: 00000000 EBX: d10c2358 ECX: c1f7c6cc EDX: c1f6ff44
[ 10.161469] ESI: 00000000 EDI: c2059900 EBP: d0e0dc4c ESP: d0e0dbe4
[ 10.162534] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
[ 10.163482] CR0: 80050033 CR2: 00000198 CR3: 10d94660 CR4: 000006b0
[ 10.164535] Call Trace:
[ 10.164993] ? paravirt_sched_clock+0x9/0xd
[ 10.165727] ? sched_clock+0x9/0xc
[ 10.166329] ? sched_clock_cpu+0x19/0xe9
[ 10.166991] ? lock_release+0x13e/0x36c
[ 10.167652] rt6_dump_route+0x4c/0x56
[ 10.168276] fib6_dump_node+0x1d/0x3d
[ 10.168913] fib6_walk_continue+0xab/0x167
[ 10.169611] fib6_walk+0x2a/0x40
[ 10.170182] inet6_dump_fib+0xfb/0x1e0
[ 10.170855] netlink_dump+0xcd/0x21f
This happens when the loopback device is set down and a ipv6 fib route
dump is requested.
The ipv6 route dump code passes ip6_null_entry to rt6_fill_node. This
route uses the loopback device but does not have idev set. When the
loopback is set down, the netif_running check added by a1a22c1206 fails
and the fill_node descends to checking rt->rt6i_idev for
ignore_routes_with_linkdown. Since idev is null for the ip6_null_entry
route it triggers the BUG.
The null_entry route should not be processed in a dump request. Catch
and ignore.
Fixes: a1a22c1206("net: ipv6: Keep nexthop of multipath route on admin down")
Signed-off-by: David Ahern <dsa@...ulusnetworks.com>
---
net/ipv6/route.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 4b1f0f98a0e9..47499ed429da 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3320,6 +3320,10 @@ static int rt6_fill_node(struct net *net,
int rt6_dump_route(struct rt6_info *rt, void *p_arg)
{
struct rt6_rtnl_dump_arg *arg = (struct rt6_rtnl_dump_arg *) p_arg;
+ struct net *net = arg->net;
+
+ if (rt == net->ipv6.ip6_null_entry)
+ return 0;
if (nlmsg_len(arg->cb->nlh) >= sizeof(struct rtmsg)) {
struct rtmsg *rtm = nlmsg_data(arg->cb->nlh);
@@ -3332,7 +3336,7 @@ int rt6_dump_route(struct rt6_info *rt, void *p_arg)
}
}
- return rt6_fill_node(arg->net,
+ return rt6_fill_node(net,
arg->skb, rt, NULL, NULL, 0, RTM_NEWROUTE,
NETLINK_CB(arg->cb->skb).portid, arg->cb->nlh->nlmsg_seq,
NLM_F_MULTI);
--
2.1.4
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