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

From: syzbot
Date: Sat May 18 2019 - 03:30:30 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 510e2ced ipv6: fix src addr routing with the exception table
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=15345db2a00000
kernel config: https://syzkaller.appspot.com/x/.config?x=82f0809e8f0a8c87
dashboard link: https://syzkaller.appspot.com/bug?extid=21ad49ad4c11cbfba8d7
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1648fdb2a00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16437cf8a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+21ad49ad4c11cbfba8d7@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: slab-out-of-bounds in __lock_acquire+0x3ba2/0x5490 kernel/locking/lockdep.c:3664
Read of size 8 at addr ffff88821640d0c0 by task syz-executor701/9065

CPU: 0 PID: 9065 Comm: syz-executor701 Not tainted 5.1.0+ #17
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+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
__kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
kasan_report+0x12/0x20 mm/kasan/common.c:614
__asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
__lock_acquire+0x3ba2/0x5490 kernel/locking/lockdep.c:3664
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4302
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:338 [inline]
rhashtable_walk_enter+0xf9/0x390 lib/rhashtable.c:669
__tipc_dump_start+0x1fa/0x3c0 net/tipc/socket.c:3414
tipc_dump_start+0x70/0x90 net/tipc/socket.c:3396
__netlink_dump_start+0x4fb/0x7e0 net/netlink/af_netlink.c:2351
netlink_dump_start include/linux/netlink.h:226 [inline]
tipc_sock_diag_handler_dump+0x1d9/0x270 net/tipc/diag.c:91
__sock_diag_cmd net/core/sock_diag.c:232 [inline]
sock_diag_rcv_msg+0x322/0x410 net/core/sock_diag.c:263
netlink_rcv_skb+0x17a/0x460 net/netlink/af_netlink.c:2486
sock_diag_rcv+0x2b/0x40 net/core/sock_diag.c:274
netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
netlink_unicast+0x536/0x720 net/netlink/af_netlink.c:1337
netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1926
sock_sendmsg_nosec net/socket.c:660 [inline]
sock_sendmsg+0x12e/0x170 net/socket.c:671
___sys_sendmsg+0x81d/0x960 net/socket.c:2292
__sys_sendmsg+0x105/0x1d0 net/socket.c:2330
__do_sys_sendmsg net/socket.c:2339 [inline]
__se_sys_sendmsg net/socket.c:2337 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2337
do_syscall_64+0x103/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4401f9
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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffce5915488 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004401f9
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401a80
R13: 0000000000401b10 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 1:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc mm/kasan/common.c:489 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497
slab_post_alloc_hook mm/slab.h:437 [inline]
slab_alloc mm/slab.c:3356 [inline]
kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3518
kmem_cache_zalloc include/linux/slab.h:732 [inline]
__kernfs_new_node+0xf0/0x6c0 fs/kernfs/dir.c:632
kernfs_new_node+0x96/0x120 fs/kernfs/dir.c:698
__kernfs_create_file+0x51/0x340 fs/kernfs/file.c:1002
sysfs_add_file_mode_ns+0x222/0x560 fs/sysfs/file.c:305
create_files fs/sysfs/group.c:63 [inline]
internal_create_group+0x35b/0xc40 fs/sysfs/group.c:148
sysfs_create_group fs/sysfs/group.c:174 [inline]
sysfs_create_groups fs/sysfs/group.c:201 [inline]
sysfs_create_groups+0x9b/0x141 fs/sysfs/group.c:191
device_add_groups drivers/base/core.c:1288 [inline]
device_add_attrs drivers/base/core.c:1436 [inline]
device_add+0x80f/0x17a0 drivers/base/core.c:2080
netdev_register_kobject+0x183/0x3b0 net/core/net-sysfs.c:1750
register_netdevice+0x878/0xff0 net/core/dev.c:8743
register_netdev+0x30/0x50 net/core/dev.c:8861
vti6_init_net+0x518/0x820 net/ipv6/ip6_vti.c:1126
ops_init+0xb6/0x410 net/core/net_namespace.c:129
__register_pernet_operations net/core/net_namespace.c:1092 [inline]
register_pernet_operations+0x382/0x7f0 net/core/net_namespace.c:1163
register_pernet_device+0x2a/0x80 net/core/net_namespace.c:1250
vti6_tunnel_init+0x19/0x176 net/ipv6/ip6_vti.c:1195
do_one_initcall+0x109/0x7ca init/main.c:914
do_initcall_level init/main.c:982 [inline]
do_initcalls init/main.c:990 [inline]
do_basic_setup init/main.c:1008 [inline]
kernel_init_freeable+0x4da/0x5c9 init/main.c:1168
kernel_init+0x12/0x1c5 init/main.c:1086
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff88821640d000
which belongs to the cache kernfs_node_cache of size 160
The buggy address is located 32 bytes to the right of
160-byte region [ffff88821640d000, ffff88821640d0a0)
The buggy address belongs to the page:
page:ffffea0008590340 count:1 mapcount:0 mapping:ffff88821bc45500 index:0xffff88821640dfee
flags: 0x6fffc0000000200(slab)
raw: 06fffc0000000200 ffffea00085a7c48 ffffea0008590388 ffff88821bc45500
raw: ffff88821640dfee ffff88821640d000 0000000100000012 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88821640cf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88821640d000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

ffff88821640d080: 00 00 00 00 fc fc fc fc fc fc fc fc 00 00 00 00

^
ffff88821640d100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88821640d180: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
==================================================================

---
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