syzbot


KASAN: use-after-free Write in sctp_auth_shkey_hold

Status: fixed on 2021/11/10 00:50
Reported-by: syzbot+b774577370208727d12b@syzkaller.appspotmail.com
Fix commit: 58acd1009226 sctp: update active_key for asoc when old key is being replaced
First crash: 405d, last: 393d

Cause bisection: introduced by (bisect log) :
commit 56dd525abd56f7acd7b44a52935726e3ada4916c
Author: Xin Long <lucien.xin@gmail.com>
Date: Mon Aug 19 14:02:49 2019 +0000

  sctp: add SCTP_AUTH_SUPPORTED sockopt

Crash: KASAN: use-after-free Read in sctp_packet_append_chunk (log)
Repro: C syz .config

Sample crash report:
==================================================================
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/asm-generic/atomic-instrumented.h:111 [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 ffff88802117d258 by task syz-executor205/8436

CPU: 1 PID: 8436 Comm: syz-executor205 Tainted: G        W         5.14.0-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:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:436
 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/asm-generic/atomic-instrumented.h:111 [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:131 [inline]
 sctp_sendmsg_to_asoc+0x152e/0x2180 net/sctp/socket.c:1865
 sctp_sendmsg+0x103b/0x1d30 net/sctp/socket.c:2027
 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:821
 sock_sendmsg_nosec net/socket.c:703 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:723
 __sys_sendto+0x21c/0x320 net/socket.c:2019
 __do_sys_sendto net/socket.c:2031 [inline]
 __se_sys_sendto net/socket.c:2027 [inline]
 __x64_sys_sendto+0xdd/0x1b0 net/socket.c:2027
 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+0x44/0xae
RIP: 0033:0x43efe9
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdbdc702a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0100000000000000 RCX: 000000000043efe9
RDX: 000000000000ffa0 RSI: 0000000020000140 RDI: 0000000000000003
RBP: 0000000000402fd0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000403060
R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488

Allocated by task 8436:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 ____kasan_kmalloc mm/kasan/common.c:472 [inline]
 __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:591 [inline]
 kzalloc include/linux/slab.h:721 [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+0x1829/0x2250 net/sctp/associola.c:298
 sctp_connect_new_asoc+0x1ac/0x770 net/sctp/socket.c:1088
 __sctp_connect+0x3d0/0xc30 net/sctp/socket.c:1194
 sctp_connect net/sctp/socket.c:4808 [inline]
 sctp_inet_connect+0x15e/0x200 net/sctp/socket.c:4823
 __sys_connect_file+0x155/0x1a0 net/socket.c:1879
 __sys_connect+0x161/0x190 net/socket.c:1896
 __do_sys_connect net/socket.c:1906 [inline]
 __se_sys_connect net/socket.c:1903 [inline]
 __x64_sys_connect+0x6f/0xb0 net/socket.c:1903
 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+0x44/0xae

Freed by task 8436:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:374
 kasan_slab_free include/linux/kasan.h:229 [inline]
 slab_free_hook mm/slub.c:1650 [inline]
 slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1675
 slab_free mm/slub.c:3235 [inline]
 kfree+0xeb/0x650 mm/slub.c:4295
 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+0x508/0x6d0 net/sctp/auth.c:862
 sctp_setsockopt_auth_key net/sctp/socket.c:3643 [inline]
 sctp_setsockopt+0x4bbc/0xa880 net/sctp/socket.c:4686
 __sys_setsockopt+0x2db/0x610 net/socket.c:2159
 __do_sys_setsockopt net/socket.c:2170 [inline]
 __se_sys_setsockopt net/socket.c:2167 [inline]
 __x64_sys_setsockopt+0xba/0x150 net/socket.c:2167
 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+0x44/0xae

The buggy address belongs to the object at ffff88802117d240
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 24 bytes inside of
 32-byte region [ffff88802117d240, ffff88802117d260)
The buggy address belongs to the page:
page:ffffea0000845f40 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802117d980 pfn:0x2117d
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00051e2800 0000000500000005 ffff888010841500
raw: ffff88802117d980 0000000080400034 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, ts 9952055174, free_ts 9918160267
 prep_new_page mm/page_alloc.c:2433 [inline]
 get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4166
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5374
 alloc_page_interleave+0x1e/0x200 mm/mempolicy.c:2119
 alloc_pages+0x238/0x2a0 mm/mempolicy.c:2242
 alloc_slab_page mm/slub.c:1713 [inline]
 allocate_slab+0x32b/0x4c0 mm/slub.c:1853
 new_slab mm/slub.c:1916 [inline]
 new_slab_objects mm/slub.c:2662 [inline]
 ___slab_alloc+0x4ba/0x820 mm/slub.c:2825
 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2865
 slab_alloc_node mm/slub.c:2947 [inline]
 slab_alloc mm/slub.c:2989 [inline]
 __kmalloc+0x312/0x330 mm/slub.c:4133
 kmalloc include/linux/slab.h:596 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 kobject_get_path+0xbe/0x230 lib/kobject.c:179
 kobject_uevent_env+0x265/0x1650 lib/kobject_uevent.c:529
 driver_register+0x2db/0x3a0 drivers/base/driver.c:179
 usb_serial_register drivers/usb/serial/usb-serial.c:1439 [inline]
 usb_serial_register_drivers+0x5b9/0xc10 drivers/usb/serial/usb-serial.c:1517
 do_one_initcall+0x103/0x650 init/main.c:1282
 do_initcall_level init/main.c:1355 [inline]
 do_initcalls init/main.c:1371 [inline]
 do_basic_setup init/main.c:1391 [inline]
 kernel_init_freeable+0x6b8/0x741 init/main.c:1593
 kernel_init+0x1a/0x1d0 init/main.c:1485
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1343 [inline]
 free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1394
 free_unref_page_prepare mm/page_alloc.c:3329 [inline]
 free_unref_page+0x19/0x690 mm/page_alloc.c:3408
 __vunmap+0x783/0xb70 mm/vmalloc.c:2587
 free_work+0x58/0x70 mm/vmalloc.c:82
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Memory state around the buggy address:
 ffff88802117d100: fa fb fb fb fc fc fc fc 00 00 00 00 fc fc fc fc
 ffff88802117d180: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
>ffff88802117d200: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
                                                    ^
 ffff88802117d280: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
 ffff88802117d300: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
==================================================================

Crashes (4):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-net-this-kasan-gce 2021/07/20 08:29 net 6f20c8adb181 bc48c9ab .config log report syz C KASAN: use-after-free Write in sctp_auth_shkey_hold
ci-upstream-net-kasan-gce 2021/07/20 08:05 net-next 0d6835ffe50c bc48c9ab .config log report syz C KASAN: use-after-free Write in sctp_auth_shkey_hold
ci-upstream-net-kasan-gce 2021/07/20 07:35 net-next 0d6835ffe50c bc48c9ab .config log report info KASAN: use-after-free Write in sctp_auth_shkey_hold
ci-upstream-net-kasan-gce 2021/07/07 13:42 net-next 5e437416ff66 4846d5c1 .config log report info KASAN: use-after-free Write in sctp_auth_shkey_hold