KASAN: slab-out-of-bounds Read in __sctp_v6_cmp_addr

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
83beed7b2b26f232d782127792dd0cd4362fdc41 (Fri Apr 20 17:56:32 2018 +0000)
Merge branch 'fixes' of
git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=cd494c1dd681d4d93ebb

So far this crash happened 305 times on net-next, upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6684817483628544
syzkaller reproducer:
https://syzkaller.appspot.com/x/repro.syz?id=6321732692475904
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=5381423422767104
Kernel config:
https://syzkaller.appspot.com/x/.config?id=1808800213120130118
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+cd494c...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for
details.
If you forward the report, please keep this part and the footer.

==================================================================
BUG: KASAN: slab-out-of-bounds in ipv6_addr_equal include/net/ipv6.h:507
[inline]
BUG: KASAN: slab-out-of-bounds in __sctp_v6_cmp_addr+0x4c7/0x530
net/sctp/ipv6.c:580
Read of size 8 at addr ffff8801b58626d0 by task syzkaller106428/4452

CPU: 1 PID: 4452 Comm: syzkaller106428 Not tainted 4.17.0-rc1+ #10
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_load8_noabort+0x14/0x20 mm/kasan/report.c:433
ipv6_addr_equal include/net/ipv6.h:507 [inline]
__sctp_v6_cmp_addr+0x4c7/0x530 net/sctp/ipv6.c:580
sctp_inet6_cmp_addr+0x169/0x1a0 net/sctp/ipv6.c:898
sctp_bind_addr_conflict+0x28c/0x470 net/sctp/bind_addr.c:368
sctp_get_port_local+0x9fc/0x1540 net/sctp/socket.c:7515
sctp_do_bind+0x21c/0x5f0 net/sctp/socket.c:435
sctp_bindx_add+0x90/0x1a0 net/sctp/socket.c:529
sctp_setsockopt_bindx+0x2ad/0x320 net/sctp/socket.c:1058
sctp_setsockopt+0x12c4/0x7000 net/sctp/socket.c:4227
sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3039
__sys_setsockopt+0x1bd/0x390 net/socket.c:1903
__do_sys_setsockopt net/socket.c:1914 [inline]
__se_sys_setsockopt net/socket.c:1911 [inline]
__x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445839
RSP: 002b:00007fbe3f0fdd98 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000006dac24 RCX: 0000000000445839
RDX: 0000000000000064 RSI: 0000000000000084 RDI: 0000000000000004
RBP: 00000000006dac20 R08: 0000000000000010 R09: 000000000000a6fe
R10: 00000000205ba000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc1404827f R14: 00007fbe3f0fe9c0 R15: 0000000000000003

Allocated by task 4452:
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
__do_kmalloc_node mm/slab.c:3682 [inline]
__kmalloc_node+0x47/0x70 mm/slab.c:3689
kmalloc_node include/linux/slab.h:554 [inline]
kvmalloc_node+0x6b/0x100 mm/util.c:421
kvmalloc include/linux/mm.h:550 [inline]
vmemdup_user+0x2d/0xa0 mm/util.c:186
sctp_setsockopt_bindx+0x5d/0x320 net/sctp/socket.c:1022
sctp_setsockopt+0x12c4/0x7000 net/sctp/socket.c:4227
sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3039
__sys_setsockopt+0x1bd/0x390 net/socket.c:1903
__do_sys_setsockopt net/socket.c:1914 [inline]
__se_sys_setsockopt net/socket.c:1911 [inline]
__x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 2818:
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]
kfree+0xd9/0x260 mm/slab.c:3813
single_release+0x8f/0xb0 fs/seq_file.c:609
__fput+0x34d/0x890 fs/file_table.c:209
____fput+0x15/0x20 fs/file_table.c:243
task_work_run+0x1e4/0x290 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x2bd/0x310 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801b58626c0
which belongs to the cache kmalloc-32 of size 32
The buggy address is located 16 bytes inside of
32-byte region [ffff8801b58626c0, ffff8801b58626e0)
The buggy address belongs to the page:
page:ffffea0006d61880 count:1 mapcount:0 mapping:ffff8801b5862000
index:0xffff8801b5862fc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801b5862000 ffff8801b5862fc1 0000000100000032
raw: ffffea0006ddd1e0 ffffea0006dd2860 ffff8801da8001c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801b5862580: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
ffff8801b5862600: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
> ffff8801b5862680: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc
^
ffff8801b5862700: 00 00 00 00 fc fc fc fc 00 00 04 fc fc fc fc fc
ffff8801b5862780: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
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[Xin Long]

Two v4 addresses went into ipv6_addr_equal, this happens when one
v4 socket bind v4 addr A, then another v6 socket tries to bind the
same v4 addr A.

This is an old issue, I will send a fix soon. Thanks.

> --
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> the body of a message to majo...@vger.kernel.org
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[Dmitry Vyukov]

For patch testing testing purposes:

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
master

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[Dmitry Vyukov]

And now with exact commit and a patch:

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
867ab4b2fcc3f840e9cc378a812e07f850795e6f

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer still triggered
crash:
KASAN: slab-out-of-bounds Read in __sctp_v6_cmp_addr

IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
8021q: adding VLAN 0 to HW filter on device team0

==================================================================
BUG: KASAN: slab-out-of-bounds in ipv6_addr_equal include/net/ipv6.h:507
[inline]
BUG: KASAN: slab-out-of-bounds in __sctp_v6_cmp_addr+0x4c7/0x530
net/sctp/ipv6.c:580

Read of size 8 at addr ffff8801ad2d1b10 by task syz-executor5/6819

CPU: 1 PID: 6819 Comm: syz-executor5 Not tainted 4.17.0-rc2+ #1

RIP: 0033:0x455389
RSP: 002b:00007f2ced61ec68 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f2ced61f6d4 RCX: 0000000000455389

RDX: 0000000000000064 RSI: 0000000000000084 RDI: 0000000000000004

RBP: 000000000072bea0 R08: 0000000000000010 R09: 0000000000000000
R10: 00000000205ba000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000005a3 R14: 00000000006fb7e8 R15: 0000000000000000

Allocated by task 6819:

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
__do_kmalloc_node mm/slab.c:3682 [inline]
__kmalloc_node+0x47/0x70 mm/slab.c:3689
kmalloc_node include/linux/slab.h:554 [inline]
kvmalloc_node+0x6b/0x100 mm/util.c:421
kvmalloc include/linux/mm.h:550 [inline]
vmemdup_user+0x2d/0xa0 mm/util.c:186
sctp_setsockopt_bindx+0x5d/0x320 net/sctp/socket.c:1022
sctp_setsockopt+0x12c4/0x7000 net/sctp/socket.c:4227
sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3039
__sys_setsockopt+0x1bd/0x390 net/socket.c:1903
__do_sys_setsockopt net/socket.c:1914 [inline]
__se_sys_setsockopt net/socket.c:1911 [inline]
__x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 5610:

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]
kfree+0xd9/0x260 mm/slab.c:3813

load_elf_binary+0x463e/0x5610 fs/binfmt_elf.c:1108
search_binary_handler+0x17d/0x570 fs/exec.c:1653
exec_binprm fs/exec.c:1695 [inline]
do_execveat_common.isra.34+0x16ce/0x2590 fs/exec.c:1817
do_execve fs/exec.c:1862 [inline]
__do_sys_execve fs/exec.c:1943 [inline]
__se_sys_execve fs/exec.c:1938 [inline]
__x64_sys_execve+0x8d/0xb0 fs/exec.c:1938
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801ad2d1b00

which belongs to the cache kmalloc-32 of size 32
The buggy address is located 16 bytes inside of

32-byte region [ffff8801ad2d1b00, ffff8801ad2d1b20)

The buggy address belongs to the page:

page:ffffea0006b4b440 count:1 mapcount:0 mapping:ffff8801ad2d1000
index:0xffff8801ad2d1fc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801ad2d1000 ffff8801ad2d1fc1 000000010000002c
raw: ffffea0007404160 ffffea0006b6afa0 ffff8801da8001c0 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff8801ad2d1a00: 00 00 04 fc fc fc fc fc 00 00 05 fc fc fc fc fc
ffff8801ad2d1a80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
> ffff8801ad2d1b00: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
^
ffff8801ad2d1b80: 00 00 00 00 fc fc fc fc fb fb fb fb fc fc fc fc
ffff8801ad2d1c00: 00 00 04 fc fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================


Tested on upstream commit
6d08b06e67cd117f6992c46611dfb4ce267cd71e (Mon Apr 23 02:20:09 2018 +0000)
Linux 4.17-rc2

compiler: gcc (GCC) 8.0.1 20180413 (experimental)

Kernel config:
https://syzkaller.appspot.com/x/.config?id=-1013156075036643828
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=4905856726466560

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer still triggered
crash:
KASAN: slab-out-of-bounds Read in __sctp_v6_cmp_addr

IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
8021q: adding VLAN 0 to HW filter on device team0
8021q: adding VLAN 0 to HW filter on device team0

==================================================================
BUG: KASAN: slab-out-of-bounds in ipv6_addr_equal include/net/ipv6.h:507
[inline]
BUG: KASAN: slab-out-of-bounds in __sctp_v6_cmp_addr+0x4c7/0x530
net/sctp/ipv6.c:580

Read of size 8 at addr ffff8801adf1d810 by task syz-executor3/6781

CPU: 0 PID: 6781 Comm: syz-executor3 Not tainted 4.17.0-rc1+ #1

RIP: 0033:0x455389
RSP: 002b:00007fe32e959c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007fe32e95a6d4 RCX: 0000000000455389

RDX: 0000000000000064 RSI: 0000000000000084 RDI: 0000000000000004

RBP: 000000000072bea0 R08: 0000000000000010 R09: 0000000000000000
R10: 00000000205ba000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000005a3 R14: 00000000006fb7e8 R15: 0000000000000000

Allocated by task 6781:

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
__do_kmalloc_node mm/slab.c:3682 [inline]
__kmalloc_node+0x47/0x70 mm/slab.c:3689
kmalloc_node include/linux/slab.h:554 [inline]
kvmalloc_node+0x6b/0x100 mm/util.c:421
kvmalloc include/linux/mm.h:550 [inline]
vmemdup_user+0x2d/0xa0 mm/util.c:186
sctp_setsockopt_bindx+0x5d/0x320 net/sctp/socket.c:1022
sctp_setsockopt+0x12c4/0x7000 net/sctp/socket.c:4227
sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3039
__sys_setsockopt+0x1bd/0x390 net/socket.c:1903
__do_sys_setsockopt net/socket.c:1914 [inline]
__se_sys_setsockopt net/socket.c:1911 [inline]
__x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 5611:

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]
kfree+0xd9/0x260 mm/slab.c:3813

load_elf_binary+0x463e/0x5610 fs/binfmt_elf.c:1108
search_binary_handler+0x17d/0x570 fs/exec.c:1653
exec_binprm fs/exec.c:1695 [inline]
do_execveat_common.isra.34+0x16ce/0x2590 fs/exec.c:1817
do_execve fs/exec.c:1862 [inline]
__do_sys_execve fs/exec.c:1943 [inline]
__se_sys_execve fs/exec.c:1938 [inline]
__x64_sys_execve+0x8d/0xb0 fs/exec.c:1938
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287

entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801adf1d800

which belongs to the cache kmalloc-32 of size 32
The buggy address is located 16 bytes inside of

32-byte region [ffff8801adf1d800, ffff8801adf1d820)

The buggy address belongs to the page:

page:ffffea0006b7c740 count:1 mapcount:0 mapping:ffff8801adf1d000
index:0xffff8801adf1dfc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801adf1d000 ffff8801adf1dfc1 0000000100000006
raw: ffffea0006b87620 ffffea00075c14e0 ffff8801da8001c0 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff8801adf1d700: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
ffff8801adf1d780: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
> ffff8801adf1d800: 00 00 fc fc fc fc fc fc 00 00 00 00 fc fc fc fc
^
ffff8801adf1d880: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
ffff8801adf1d900: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================


Tested on git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
commit
867ab4b2fcc3f840e9cc378a812e07f850795e6f (Mon Apr 23 00:14:29 2018 +0000)
Merge tag 'drm-fixes-for-v4.17-rc2' of
git://people.freedesktop.org/~airlied/linux

compiler: gcc (GCC) 8.0.1 20180413 (experimental)

Patch: https://syzkaller.appspot.com/x/patch.diff?id=6342587174617088
Kernel config:
https://syzkaller.appspot.com/x/.config?id=1808800213120130118
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=4756246708092928