syzbot


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

Status: fixed on 2018/11/12 21:25
Subsystems: sctp
[Documentation on labels]
Reported-by: syzbot+5da0d0a72a9e7d791748@syzkaller.appspotmail.com
Fix commit: 713358369382 sctp: check policy more carefully when getting pr status
First crash: 2060d, last: 2060d
Discussions (6)
Title Replies (including bot) Last reply
[PATCH 4.19 00/24] 4.19.1-stable review 37 (37) 2019/02/21 12:50
[PATCH net] sctp: check policy more carefully when getting pr status 2 (2) 2018/10/30 03:51
KASAN: slab-out-of-bounds Read in sctp_getsockopt 3 (4) 2018/10/29 06:50
[PATCH v2] sctp: socket.c validate sprstat_policy 3 (3) 2018/10/28 08:42
[PATCH] sctp: socket.c validate sprstat_policy 3 (3) 2018/10/28 00:03
[PATCH] sctp: socket.c validate sprstat_policy 3 (3) 2018/10/27 20:53

Sample crash report:
audit: type=1400 audit(1540511784.284:36): avc:  denied  { map } for  pid=5526 comm="syz-executor435" path="/root/syz-executor435209504" dev="sda1" ino=16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
==================================================================
BUG: KASAN: slab-out-of-bounds in sctp_getsockopt_pr_streamstatus net/sctp/socket.c:7174 [inline]
BUG: KASAN: slab-out-of-bounds in sctp_getsockopt+0x7516/0x7cc2 net/sctp/socket.c:7582
Read of size 8 at addr ffff8801ca1ff168 by task syz-executor435/5529

CPU: 1 PID: 5529 Comm: syz-executor435 Not tainted 4.19.0+ #82
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+0x244/0x39d lib/dump_stack.c:113
 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 sctp_getsockopt_pr_streamstatus net/sctp/socket.c:7174 [inline]
 sctp_getsockopt+0x7516/0x7cc2 net/sctp/socket.c:7582
 sock_common_getsockopt+0x9a/0xe0 net/core/sock.c:2937
 __sys_getsockopt+0x1ad/0x390 net/socket.c:1939
 __do_sys_getsockopt net/socket.c:1950 [inline]
 __se_sys_getsockopt net/socket.c:1947 [inline]
 __x64_sys_getsockopt+0xbe/0x150 net/socket.c:1947
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445789
Code: e8 6c b6 02 00 48 83 c4 18 c3 0f 1f 80 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 0f 83 2b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ff683eb6db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00000000006dac48 RCX: 0000000000445789
RDX: 0000000000000074 RSI: 0000000000000084 RDI: 0000000000000003
RBP: 00000000006dac40 R08: 0000000020000040 R09: 0000000000000000
R10: 0000000020000080 R11: 0000000000000246 R12: 00000000006dac4c
R13: 00007ffedd6edd7f R14: 00007ff683eb79c0 R15: 00000000006dad2c

Allocated by task 5528:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620
 kmalloc include/linux/slab.h:513 [inline]
 kzalloc include/linux/slab.h:707 [inline]
 sctp_stream_init_ext+0x4f/0xf0 net/sctp/stream.c:237
 sctp_sendmsg_to_asoc+0x1308/0x1a20 net/sctp/socket.c:1896
 sctp_sendmsg+0x13c2/0x1da0 net/sctp/socket.c:2113
 inet_sendmsg+0x1a1/0x690 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:631
 __sys_sendto+0x3d7/0x670 net/socket.c:1788
 __do_sys_sendto net/socket.c:1800 [inline]
 __se_sys_sendto net/socket.c:1796 [inline]
 __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1796
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4060:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xcf/0x230 mm/slab.c:3813
 free_rb_tree_fname+0x85/0xe0 fs/ext4/dir.c:404
 ext4_htree_free_dir_info fs/ext4/dir.c:426 [inline]
 ext4_release_dir+0x44/0x60 fs/ext4/dir.c:624
 __fput+0x385/0xa30 fs/file_table.c:278
 ____fput+0x15/0x20 fs/file_table.c:309
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801ca1ff100
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 8 bytes to the right of
 96-byte region [ffff8801ca1ff100, ffff8801ca1ff160)
The buggy address belongs to the page:
page:ffffea0007287fc0 count:1 mapcount:0 mapping:ffff8801da8004c0 index:0xffff8801ca1ff200
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea000728ac48 ffffea00071ea348 ffff8801da8004c0
raw: ffff8801ca1ff200 ffff8801ca1ff000 000000010000001b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ca1ff000: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
 ffff8801ca1ff080: 00 00 00 00 00 00 00 00 05 fc fc fc fc fc fc fc
>ffff8801ca1ff100: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
                                                          ^
 ffff8801ca1ff180: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8801ca1ff200: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/10/26 00:00 upstream bd6bf7c10484 a8292de9 .config console log report syz C ci-upstream-kasan-gce-selinux-root
2018/10/25 23:58 upstream bd6bf7c10484 a8292de9 .config console log report syz C ci-upstream-kasan-gce
2018/10/25 23:58 upstream bd6bf7c10484 a8292de9 .config console log report syz C ci-upstream-kasan-gce-smack-root
2018/10/25 23:31 upstream bd6bf7c10484 a8292de9 .config console log report syz C ci-upstream-kasan-gce-root
2018/10/26 00:00 upstream bd6bf7c10484 a8292de9 .config console log report syz C ci-upstream-kasan-gce-386
2018/10/25 23:58 net-old 42d0f71c9b5f a8292de9 .config console log report syz C ci-upstream-net-this-kasan-gce
2018/10/25 23:59 net-next-old 44adbac8f721 a8292de9 .config console log report syz C ci-upstream-net-kasan-gce
2018/10/26 02:13 linux-next 8c60c36d0b8c a8292de9 .config console log report syz C ci-upstream-linux-next-kasan-gce-root
2018/10/25 21:46 upstream bd6bf7c10484 a8292de9 .config console log report ci-upstream-kasan-gce-root
* Struck through repros no longer work on HEAD.