[syzbot] KASAN: use-after-free Write in sctp_auth_shkey_hold (2)

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Sep 26, 2022, 2:00:39 PMSep 26
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Hello,

syzbot found the following issue on:

HEAD commit: cb71b93c2dc3 Add linux-next specific files for 20220628
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12e40342080000
kernel config: https://syzkaller.appspot.com/x/.config?x=badbc1adb2d582eb
dashboard link: https://syzkaller.appspot.com/bug?extid=a236dd8e9622ed8954a3
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1689249a080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1618ab1c080000

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1155cda4080000
final oops: https://syzkaller.appspot.com/x/report.txt?x=1355cda4080000
console output: https://syzkaller.appspot.com/x/log.txt?x=1555cda4080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a236dd...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: use-after-free in atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline]
BUG: KASAN: use-after-free in __refcount_add include/linux/refcount.h:193 [inline]
BUG: KASAN: use-after-free in __refcount_inc include/linux/refcount.h:250 [inline]
BUG: KASAN: use-after-free in refcount_inc include/linux/refcount.h:267 [inline]
BUG: KASAN: use-after-free in sctp_auth_shkey_hold+0x22/0xa0 net/sctp/auth.c:112
Write of size 4 at addr ffff88807cd4ad98 by task syz-executor284/3719

CPU: 0 PID: 3719 Comm: syz-executor284 Not tainted 5.19.0-rc4-next-20220628-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:317 [inline]
print_report.cold+0x2ba/0x719 mm/kasan/report.c:433
kasan_report+0xbe/0x1f0 mm/kasan/report.c:495
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline]
__refcount_add include/linux/refcount.h:193 [inline]
__refcount_inc include/linux/refcount.h:250 [inline]
refcount_inc include/linux/refcount.h:267 [inline]
sctp_auth_shkey_hold+0x22/0xa0 net/sctp/auth.c:112
sctp_set_owner_w net/sctp/socket.c:132 [inline]
sctp_sendmsg_to_asoc+0xbd5/0x1a20 net/sctp/socket.c:1863
sctp_sendmsg+0x1053/0x1d50 net/sctp/socket.c:2025
inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:819
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
__sys_sendto+0x21a/0x320 net/socket.c:2116
__do_sys_sendto net/socket.c:2128 [inline]
__se_sys_sendto net/socket.c:2124 [inline]
__x64_sys_sendto+0xdd/0x1b0 net/socket.c:2124
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7f9b40d281d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 a1 15 00 00 90 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9b40cb52d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f9b40db04b0 RCX: 00007f9b40d281d9
RDX: 0000000000000001 RSI: 0000000020000400 RDI: 0000000000000003
RBP: 00007f9b40d7d5dc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9b40cb52f0
R13: 00007f9b40db04b8 R14: 0100000000000000 R15: 0000000000022000
</TASK>

Allocated by task 3717:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
____kasan_kmalloc mm/kasan/common.c:515 [inline]
____kasan_kmalloc mm/kasan/common.c:474 [inline]
__kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:733 [inline]
sctp_auth_shkey_create+0x85/0x1f0 net/sctp/auth.c:84
sctp_auth_asoc_copy_shkeys+0x1e8/0x350 net/sctp/auth.c:363
sctp_association_init net/sctp/associola.c:257 [inline]
sctp_association_new+0x189e/0x2330 net/sctp/associola.c:298
sctp_connect_new_asoc+0x1ac/0x770 net/sctp/socket.c:1089
sctp_sendmsg_new_asoc net/sctp/socket.c:1691 [inline]
sctp_sendmsg+0x13d7/0x1d50 net/sctp/socket.c:1998
inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:819
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
__sys_sendto+0x21a/0x320 net/socket.c:2116
__do_sys_sendto net/socket.c:2128 [inline]
__se_sys_sendto net/socket.c:2124 [inline]
__x64_sys_sendto+0xdd/0x1b0 net/socket.c:2124
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x46/0xb0

Freed by task 3720:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track+0x21/0x30 mm/kasan/common.c:45
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free+0x166/0x1c0 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:200 [inline]
slab_free_hook mm/slub.c:1754 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1780
slab_free mm/slub.c:3534 [inline]
kfree+0xe2/0x4d0 mm/slub.c:4562
sctp_auth_shkey_destroy net/sctp/auth.c:101 [inline]
sctp_auth_shkey_release+0x100/0x160 net/sctp/auth.c:107
sctp_auth_set_key+0x443/0x960 net/sctp/auth.c:866
sctp_setsockopt_auth_key net/sctp/socket.c:3640 [inline]
sctp_setsockopt+0x4c33/0xa9a0 net/sctp/socket.c:4683
__sys_setsockopt+0x2d6/0x690 net/socket.c:2251
__do_sys_setsockopt net/socket.c:2262 [inline]
__se_sys_setsockopt net/socket.c:2259 [inline]
__x64_sys_setsockopt+0xba/0x150 net/socket.c:2259
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x46/0xb0

The buggy address belongs to the object at ffff88807cd4ad80
which belongs to the cache kmalloc-32 of size 32
The buggy address is located 24 bytes inside of
32-byte region [ffff88807cd4ad80, ffff88807cd4ada0)

The buggy address belongs to the physical page:
page:ffffea0001f35280 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7cd4a
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 0000000000000000 dead000000000122 ffff888011841500
raw: 0000000000000000 0000000000400040 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY), pid 3653, tgid 3653 (kworker/1:6), ts 62971434672, free_ts 62952459810
prep_new_page mm/page_alloc.c:2535 [inline]
get_page_from_freelist+0x210d/0x3a30 mm/page_alloc.c:4282
__alloc_pages+0x1c7/0x510 mm/page_alloc.c:5506
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2280
alloc_slab_page mm/slub.c:1824 [inline]
allocate_slab+0x27e/0x3d0 mm/slub.c:1969
new_slab mm/slub.c:2029 [inline]
___slab_alloc+0x89d/0xef0 mm/slub.c:3031
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3118
slab_alloc_node mm/slub.c:3209 [inline]
slab_alloc mm/slub.c:3251 [inline]
kmem_cache_alloc_trace+0x323/0x3e0 mm/slub.c:3282
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:733 [inline]
ref_tracker_alloc+0x14c/0x550 lib/ref_tracker.c:85
__netdev_tracker_alloc include/linux/netdevice.h:3960 [inline]
netdev_hold include/linux/netdevice.h:3989 [inline]
dst_init+0xe0/0x520 net/core/dst.c:52
dst_alloc+0x16b/0x1f0 net/core/dst.c:96
ip6_dst_alloc+0x2e/0x90 net/ipv6/route.c:344
icmp6_dst_alloc+0x6d/0x680 net/ipv6/route.c:3261
ndisc_send_skb+0x10eb/0x1730 net/ipv6/ndisc.c:487
ndisc_send_ns+0xa6/0x120 net/ipv6/ndisc.c:665
addrconf_dad_work+0xbf9/0x12d0 net/ipv6/addrconf.c:4171
process_one_work+0x991/0x1610 kernel/workqueue.c:2289
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1453 [inline]
free_pcp_prepare+0x5e4/0xd20 mm/page_alloc.c:1503
free_unref_page_prepare mm/page_alloc.c:3383 [inline]
free_unref_page_list+0x16f/0xb90 mm/page_alloc.c:3525
release_pages+0xbe8/0x1810 mm/swap.c:1017
tlb_batch_pages_flush+0xa8/0x1a0 mm/mmu_gather.c:58
tlb_flush_mmu_free mm/mmu_gather.c:255 [inline]
tlb_flush_mmu mm/mmu_gather.c:262 [inline]
tlb_finish_mmu+0x147/0x7e0 mm/mmu_gather.c:353
exit_mmap+0x1fe/0x720 mm/mmap.c:3212
__mmput+0x128/0x4c0 kernel/fork.c:1180
mmput+0x5c/0x70 kernel/fork.c:1201
exit_mm kernel/exit.c:510 [inline]
do_exit+0xa09/0x29f0 kernel/exit.c:782
do_group_exit+0xd2/0x2f0 kernel/exit.c:925
__do_sys_exit_group kernel/exit.c:936 [inline]
__se_sys_exit_group kernel/exit.c:934 [inline]
__x64_sys_exit_group+0x3a/0x50 kernel/exit.c:934
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x46/0xb0

Memory state around the buggy address:
ffff88807cd4ac80: 00 00 00 00 fc fc fc fc 00 00 00 00 fc fc fc fc
ffff88807cd4ad00: 00 00 00 00 fc fc fc fc fa fb fb fb fc fc fc fc
>ffff88807cd4ad80: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
^
ffff88807cd4ae00: 00 00 00 00 fc fc fc fc 00 00 00 00 fc fc fc fc
ffff88807cd4ae80: 00 00 00 00 fc fc fc fc 00 00 00 00 fc fc fc fc
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

Xin Long

unread,
Sep 27, 2022, 6:59:16 PMSep 27
to syzbot, da...@davemloft.net, edum...@google.com, ku...@kernel.org, linux-...@vger.kernel.org, linux...@vger.kernel.org, marcelo...@gmail.com, net...@vger.kernel.org, nho...@tuxdriver.com, pab...@redhat.com, syzkall...@googlegroups.com, vyas...@gmail.com
The call trace is very similar with the one fixed in:

commit 58acd10092268831e49de279446c314727101292
Author: Xin Long <lucie...@gmail.com>
Date: Tue Jul 20 16:07:01 2021 -0400

sctp: update active_key for asoc when old key is being replaced

It was caused by active_key not being updated.

"setsockopt$inet_sctp6_SCTP_AUTH_KEY(r0, 0x84, 0x17,
&(0x7f00000002c0)={0x0, 0x0, 0x1, "8b"}, 0x9) (fail_nth: 5)"

If the 5th failure is the one in sctp_auth_asoc_init_active_key(),
this same issue will be triggered.

I will prepare a fix to handle the error returned from
sctp_auth_asoc_init_active_key() in sctp_auth_set_key().

Thanks.
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