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f7225172f2
syzbot reported a use-after-free:
BUG: KASAN: use-after-free in ip6_route_mpath_notify+0xe9/0x100 net/ipv6/route.c:4180
Read of size 4 at addr ffff8801bf789cf0 by task syz-executor756/4555
CPU: 1 PID: 4555 Comm: syz-executor756 Not tainted 4.17.0-rc7+ #78
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+0x1b9/0x294 lib/dump_stack.c:113
print_address_description+0x6c/0x20b mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
__asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
ip6_route_mpath_notify+0xe9/0x100 net/ipv6/route.c:4180
ip6_route_multipath_add+0x615/0x1910 net/ipv6/route.c:4303
inet6_rtm_newroute+0xe3/0x160 net/ipv6/route.c:4391
...
Allocated by task 4555:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
dst_alloc+0xbb/0x1d0 net/core/dst.c:104
__ip6_dst_alloc+0x35/0xa0 net/ipv6/route.c:361
ip6_dst_alloc+0x29/0xb0 net/ipv6/route.c:376
ip6_route_info_create+0x4d4/0x3a30 net/ipv6/route.c:2834
ip6_route_multipath_add+0xc7e/0x1910 net/ipv6/route.c:4240
inet6_rtm_newroute+0xe3/0x160 net/ipv6/route.c:4391
...
Freed by task 4555:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kmem_cache_free+0x86/0x2d0 mm/slab.c:3756
dst_destroy+0x267/0x3c0 net/core/dst.c:140
dst_release_immediate+0x71/0x9e net/core/dst.c:205
fib6_add+0xa40/0x1650 net/ipv6/ip6_fib.c:1305
__ip6_ins_rt+0x6c/0x90 net/ipv6/route.c:1011
ip6_route_multipath_add+0x513/0x1910 net/ipv6/route.c:4267
inet6_rtm_newroute+0xe3/0x160 net/ipv6/route.c:4391
...
The problem is that rt_last can point to a deleted route if the insert
fails.
One reproducer is to insert a route and then add a multipath route that
has a duplicate nexthop.e.g,:
$ ip -6 ro add vrf red 2001:db8:101::/64 nexthop via 2001:db8:1::2
$ ip -6 ro append vrf red 2001:db8:101::/64 nexthop via 2001:db8:1::4 nexthop via 2001:db8:1::2
Fix by not setting rt_last until the it is verified the insert succeeded.
Fixes:
|
||
|---|---|---|
| .. | ||
| ila | ||
| netfilter | ||
| addrconf.c | ||
| addrconf_core.c | ||
| addrlabel.c | ||
| af_inet6.c | ||
| ah6.c | ||
| anycast.c | ||
| calipso.c | ||
| datagram.c | ||
| esp6.c | ||
| esp6_offload.c | ||
| exthdrs.c | ||
| exthdrs_core.c | ||
| exthdrs_offload.c | ||
| fib6_notifier.c | ||
| fib6_rules.c | ||
| fou6.c | ||
| icmp.c | ||
| inet6_connection_sock.c | ||
| inet6_hashtables.c | ||
| ip6_checksum.c | ||
| ip6_fib.c | ||
| ip6_flowlabel.c | ||
| ip6_gre.c | ||
| ip6_icmp.c | ||
| ip6_input.c | ||
| ip6_offload.c | ||
| ip6_offload.h | ||
| ip6_output.c | ||
| ip6_tunnel.c | ||
| ip6_udp_tunnel.c | ||
| ip6_vti.c | ||
| ip6mr.c | ||
| ipcomp6.c | ||
| ipv6_sockglue.c | ||
| Kconfig | ||
| Makefile | ||
| mcast.c | ||
| mcast_snoop.c | ||
| mip6.c | ||
| ndisc.c | ||
| netfilter.c | ||
| output_core.c | ||
| ping.c | ||
| proc.c | ||
| protocol.c | ||
| raw.c | ||
| reassembly.c | ||
| route.c | ||
| seg6.c | ||
| seg6_hmac.c | ||
| seg6_iptunnel.c | ||
| seg6_local.c | ||
| sit.c | ||
| syncookies.c | ||
| sysctl_net_ipv6.c | ||
| tcp_ipv6.c | ||
| tcpv6_offload.c | ||
| tunnel6.c | ||
| udp.c | ||
| udp_impl.h | ||
| udp_offload.c | ||
| udplite.c | ||
| xfrm6_input.c | ||
| xfrm6_mode_beet.c | ||
| xfrm6_mode_ro.c | ||
| xfrm6_mode_transport.c | ||
| xfrm6_mode_tunnel.c | ||
| xfrm6_output.c | ||
| xfrm6_policy.c | ||
| xfrm6_protocol.c | ||
| xfrm6_state.c | ||
| xfrm6_tunnel.c | ||