KASAN: slab-out-of-bounds Read in decode_session6

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syzbot

unread,
Jun 27, 2020, 3:18:13 AM6/27/20
to da...@davemloft.net, her...@gondor.apana.org.au, ku...@kernel.org, linux-...@vger.kernel.org, net...@vger.kernel.org, steffen....@secunet.com, syzkall...@googlegroups.com
Hello,

syzbot found the following crash on:

HEAD commit: b835a71e usbnet: smsc95xx: Fix use-after-free after removal
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=1565a5fd100000
kernel config: https://syzkaller.appspot.com/x/.config?x=dcc6334acae363d4
dashboard link: https://syzkaller.appspot.com/bug?extid=2bcc71839223ec82f056
compiler: gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+2bcc71...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in decode_session6+0xe7c/0x1580 net/xfrm/xfrm_policy.c:3389
Read of size 1 at addr ffff88809edddd50 by task syz-executor.5/2845

CPU: 1 PID: 2845 Comm: syz-executor.5 Not tainted 5.8.0-rc1-syzkaller #0
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+0x18f/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
decode_session6+0xe7c/0x1580 net/xfrm/xfrm_policy.c:3389
__xfrm_decode_session+0x50/0xb0 net/xfrm/xfrm_policy.c:3481
xfrm_decode_session_reverse include/net/xfrm.h:1141 [inline]
icmpv6_route_lookup+0x304/0x470 net/ipv6/icmp.c:388
icmp6_send+0x1327/0x26b0 net/ipv6/icmp.c:588
icmpv6_send+0xde/0x210 net/ipv6/ip6_icmp.c:43
ip6_link_failure+0x26/0x500 net/ipv6/route.c:2665
dst_link_failure include/net/dst.h:418 [inline]
ipip6_tunnel_xmit net/ipv6/sit.c:1042 [inline]
sit_tunnel_xmit+0x1919/0x29d0 net/ipv6/sit.c:1079
__netdev_start_xmit include/linux/netdevice.h:4611 [inline]
netdev_start_xmit include/linux/netdevice.h:4625 [inline]
xmit_one net/core/dev.c:3556 [inline]
dev_hard_start_xmit+0x193/0x950 net/core/dev.c:3572
sch_direct_xmit+0x2ea/0xc00 net/sched/sch_generic.c:313
qdisc_restart net/sched/sch_generic.c:376 [inline]
__qdisc_run+0x4b9/0x1630 net/sched/sch_generic.c:384
__dev_xmit_skb net/core/dev.c:3795 [inline]
__dev_queue_xmit+0x1995/0x2d60 net/core/dev.c:4100
neigh_output include/net/neighbour.h:509 [inline]
ip6_finish_output2+0x8b6/0x17b0 net/ipv6/ip6_output.c:117
__ip6_finish_output net/ipv6/ip6_output.c:143 [inline]
__ip6_finish_output+0x447/0xab0 net/ipv6/ip6_output.c:128
ip6_finish_output+0x34/0x1f0 net/ipv6/ip6_output.c:153
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip6_output+0x1db/0x520 net/ipv6/ip6_output.c:176
dst_output include/net/dst.h:435 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
ip6_xmit+0x1258/0x1e80 net/ipv6/ip6_output.c:280
sctp_v6_xmit+0x339/0x650 net/sctp/ipv6.c:217
sctp_packet_transmit+0x20d7/0x3240 net/sctp/output.c:629
sctp_packet_singleton net/sctp/outqueue.c:773 [inline]
sctp_outq_flush_ctrl.constprop.0+0x6d3/0xc40 net/sctp/outqueue.c:904
sctp_outq_flush+0xfb/0x2380 net/sctp/outqueue.c:1186
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1801 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1185 [inline]
sctp_do_sm+0x4d0/0x4d80 net/sctp/sm_sideeffect.c:1156
sctp_primitive_ASSOCIATE+0x98/0xc0 net/sctp/primitive.c:73
sctp_sendmsg_to_asoc+0xb44/0x2090 net/sctp/socket.c:1848
sctp_sendmsg+0x1025/0x1cf0 net/sctp/socket.c:2038
inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:814
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:672
____sys_sendmsg+0x331/0x810 net/socket.c:2352
___sys_sendmsg+0xf3/0x170 net/socket.c:2406
__sys_sendmmsg+0x195/0x480 net/socket.c:2496
__do_sys_sendmmsg net/socket.c:2525 [inline]
__se_sys_sendmmsg net/socket.c:2522 [inline]
__x64_sys_sendmmsg+0x99/0x100 net/socket.c:2522
do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45ca59
Code: Bad RIP value.
RSP: 002b:00007f677b566c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000004fd400 RCX: 000000000045ca59
RDX: 0000000000000001 RSI: 00000000200006c0 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000902 R14: 00000000004cbd15 R15: 00007f677b5676d4

Allocated by task 7426:
save_stack+0x1b/0x40 mm/kasan/common.c:48
set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
kmalloc_node include/linux/slab.h:578 [inline]
kvmalloc_node+0x61/0xf0 mm/util.c:574
kvmalloc include/linux/mm.h:753 [inline]
xt_alloc_table_info+0x3c/0xa0 net/netfilter/x_tables.c:1176
do_replace net/ipv6/netfilter/ip6_tables.c:1142 [inline]
do_ip6t_set_ctl+0x226/0x460 net/ipv6/netfilter/ip6_tables.c:1681
nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
nf_setsockopt+0x6f/0xc0 net/netfilter/nf_sockopt.c:115
ipv6_setsockopt+0x10c/0x170 net/ipv6/ipv6_sockglue.c:905
tcp_setsockopt+0x86/0xd0 net/ipv4/tcp.c:3334
__sys_setsockopt+0x24a/0x480 net/socket.c:2127
__do_sys_setsockopt net/socket.c:2143 [inline]
__se_sys_setsockopt net/socket.c:2140 [inline]
__x64_sys_setsockopt+0xba/0x150 net/socket.c:2140
do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 7135:
save_stack+0x1b/0x40 mm/kasan/common.c:48
set_track mm/kasan/common.c:56 [inline]
kasan_set_free_info mm/kasan/common.c:316 [inline]
__kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
__cache_free mm/slab.c:3426 [inline]
kfree+0x103/0x2c0 mm/slab.c:3757
sk_prot_free net/core/sock.c:1730 [inline]
__sk_destruct+0x63b/0x860 net/core/sock.c:1814
sk_destruct+0xbd/0xe0 net/core/sock.c:1829
__sk_free+0xef/0x3d0 net/core/sock.c:1840
sk_free+0x78/0xa0 net/core/sock.c:1851
deferred_put_nlk_sk+0x151/0x2e0 net/netlink/af_netlink.c:729
rcu_do_batch kernel/rcu/tree.c:2396 [inline]
rcu_core+0x5c7/0x1160 kernel/rcu/tree.c:2623
__do_softirq+0x34c/0xa60 kernel/softirq.c:292

The buggy address belongs to the object at ffff88809eddd000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1360 bytes to the right of
2048-byte region [ffff88809eddd000, ffff88809eddd800)
The buggy address belongs to the page:
page:ffffea00027b7740 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002566d88 ffffea00026a7188 ffff8880aa000e00
raw: 0000000000000000 ffff88809eddd000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809edddc00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88809edddc80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809edddd00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff88809edddd80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88809eddde00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot

unread,
Nov 1, 2020, 9:29:21 AM11/1/20
to da...@davemloft.net, her...@gondor.apana.org.au, ku...@kernel.org, linux-...@vger.kernel.org, net...@vger.kernel.org, steffen....@secunet.com, syzkall...@googlegroups.com
syzbot has found a reproducer for the following issue on:

HEAD commit: c43fd36f net: bridge: mcast: fix stub definition of br_mul..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12677e92500000
kernel config: https://syzkaller.appspot.com/x/.config?x=eac680ae76558a0e
dashboard link: https://syzkaller.appspot.com/bug?extid=2bcc71839223ec82f056
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e1b946500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1143c192500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2bcc71...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in decode_session6+0xe7c/0x1580 net/xfrm/xfrm_policy.c:3393
Read of size 1 at addr ffff8880247cb8af by task syz-executor222/8528

CPU: 0 PID: 8528 Comm: syz-executor222 Not tainted 5.10.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385
__kasan_report mm/kasan/report.c:545 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
decode_session6+0xe7c/0x1580 net/xfrm/xfrm_policy.c:3393
__xfrm_decode_session net/xfrm/xfrm_policy.c:3485 [inline]
__xfrm_policy_check+0x2fa/0x2850 net/xfrm/xfrm_policy.c:3540
__xfrm_policy_check2 include/net/xfrm.h:1097 [inline]
xfrm_policy_check include/net/xfrm.h:1106 [inline]
sctp_rcv+0x12b0/0x2e30 net/sctp/input.c:202
sctp6_rcv+0x22/0x40 net/sctp/ipv6.c:1078
ip6_protocol_deliver_rcu+0x2e8/0x1680 net/ipv6/ip6_input.c:433
ip6_input_finish+0x7f/0x160 net/ipv6/ip6_input.c:474
NF_HOOK include/linux/netfilter.h:301 [inline]
NF_HOOK include/linux/netfilter.h:295 [inline]
ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:483
dst_input include/net/dst.h:449 [inline]
ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
NF_HOOK include/linux/netfilter.h:295 [inline]
ipv6_rcv+0x28e/0x3c0 net/ipv6/ip6_input.c:307
__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5315
__netif_receive_skb+0x27/0x1c0 net/core/dev.c:5429
process_backlog+0x232/0x6c0 net/core/dev.c:6319
napi_poll net/core/dev.c:6763 [inline]
net_rx_action+0x4dc/0x1100 net/core/dev.c:6833
__do_softirq+0x2a0/0x9f6 kernel/softirq.c:298
asm_call_irq_on_stack+0xf/0x20
</IRQ>
__run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
do_softirq_own_stack+0xaa/0xd0 arch/x86/kernel/irq_64.c:77
do_softirq kernel/softirq.c:343 [inline]
do_softirq+0xb5/0xe0 kernel/softirq.c:330
__local_bh_enable_ip+0xf0/0x110 kernel/softirq.c:195
local_bh_enable include/linux/bottom_half.h:32 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:730 [inline]
ip6_finish_output2+0x71f/0x16c0 net/ipv6/ip6_output.c:118
__ip6_finish_output net/ipv6/ip6_output.c:143 [inline]
__ip6_finish_output+0x447/0xab0 net/ipv6/ip6_output.c:128
ip6_finish_output+0x34/0x1f0 net/ipv6/ip6_output.c:153
NF_HOOK_COND include/linux/netfilter.h:290 [inline]
ip6_output+0x1db/0x520 net/ipv6/ip6_output.c:176
dst_output include/net/dst.h:443 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
NF_HOOK include/linux/netfilter.h:295 [inline]
ip6_xmit+0x1258/0x1e80 net/ipv6/ip6_output.c:280
sctp_v6_xmit+0xbf3/0xfe0 net/sctp/ipv6.c:223
sctp_packet_transmit+0x1f44/0x32f0 net/sctp/output.c:627
sctp_packet_singleton net/sctp/outqueue.c:773 [inline]
sctp_outq_flush_ctrl.constprop.0+0x6d3/0xc40 net/sctp/outqueue.c:904
sctp_outq_flush+0xf3/0x2580 net/sctp/outqueue.c:1186
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1801 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1185 [inline]
sctp_do_sm+0x74e/0x5130 net/sctp/sm_sideeffect.c:1156
sctp_primitive_ASSOCIATE+0x98/0xc0 net/sctp/primitive.c:73
sctp_sendmsg_to_asoc+0xb5b/0x2140 net/sctp/socket.c:1823
sctp_sendmsg+0x103b/0x1d30 net/sctp/socket.c:2013
inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:817
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:671
__sys_sendto+0x21c/0x320 net/socket.c:1992
__do_sys_sendto net/socket.c:2004 [inline]
__se_sys_sendto net/socket.c:2000 [inline]
__x64_sys_sendto+0xdd/0x1b0 net/socket.c:2000
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x441759
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc188919d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007ffc188919f0 RCX: 0000000000441759
RDX: 0000000000034000 RSI: 0000000020847fff RDI: 0000000000000004
RBP: 0000000000000000 R08: 000000002005ffe4 R09: 000000000000001c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402f60
R13: 0000000000402ff0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 1:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:461
kmalloc include/linux/slab.h:557 [inline]
tomoyo_realpath_from_path+0xc3/0x620 security/tomoyo/realpath.c:254
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x21b/0x400 security/tomoyo/file.c:822
security_inode_getattr+0xcf/0x140 security/security.c:1279
vfs_getattr fs/stat.c:121 [inline]
vfs_statx+0x164/0x390 fs/stat.c:189
vfs_fstatat fs/stat.c:207 [inline]
vfs_lstat include/linux/fs.h:3109 [inline]
__do_sys_newlstat+0x91/0x110 fs/stat.c:362
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 1:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
__kasan_slab_free+0x102/0x140 mm/kasan/common.c:422
slab_free_hook mm/slub.c:1544 [inline]
slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1577
slab_free mm/slub.c:3142 [inline]
kfree+0xdb/0x360 mm/slub.c:4124
tomoyo_realpath_from_path+0x191/0x620 security/tomoyo/realpath.c:291
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x21b/0x400 security/tomoyo/file.c:822
security_inode_getattr+0xcf/0x140 security/security.c:1279
vfs_getattr fs/stat.c:121 [inline]
vfs_statx+0x164/0x390 fs/stat.c:189
vfs_fstatat fs/stat.c:207 [inline]
vfs_lstat include/linux/fs.h:3109 [inline]
__do_sys_newlstat+0x91/0x110 fs/stat.c:362
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8880247ca000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 2223 bytes to the right of
4096-byte region [ffff8880247ca000, ffff8880247cb000)
The buggy address belongs to the page:
page:00000000ecac6d17 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x247c8
head:00000000ecac6d17 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010042140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880247cb780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880247cb800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880247cb880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff8880247cb900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880247cb980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

syzbot

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Jan 9, 2024, 1:18:21 PMJan 9
to syzkall...@googlegroups.com
Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.
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