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KASAN: use-after-free Read in tomoyo_realpath_from_path

Status: fixed on 2020/02/14 01:19
Subsystems: tomoyo
[Documentation on labels]
Reported-by: syzbot+0341f6a4d729d4e0acf1@syzkaller.appspotmail.com
Fix commit: 6f7c41374b62 tomoyo: Don't use nifty names on sockets.
First crash: 1996d, last: 1802d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Discussions (6)
Title Replies (including bot) Last reply
[PATCH 5.4 000/191] 5.4.8-stable review 215 (215) 2020/01/06 09:03
[PATCH] tomoyo: Don't check open/getattr permission on sockets. 9 (9) 2019/08/22 15:47
Reminder: 2 open syzbot bugs in "security/tomoyo" subsystem 1 (1) 2019/07/24 02:42
Reminder: 2 open syzbot bugs in "security/tomoyo" subsystem 1 (1) 2019/07/02 05:14
Re: KASAN: use-after-free Read in =?ISO-2022-JP?B?dG9tb3lvX3JlYWxwYXRo?= =?ISO-2022-JP?B?X2Zyb21fcGF0aA==?= 1 (1) 2019/06/06 05:20
KASAN: use-after-free Read in tomoyo_realpath_from_path 2 (3) 2019/06/06 02:08
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2019/08/22 10:42 17m penguin-kernel@i-love.sakura.ne.jp patch upstream OK

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in tomoyo_get_socket_name security/tomoyo/realpath.c:238 [inline]
BUG: KASAN: use-after-free in tomoyo_realpath_from_path+0x722/0x7a0 security/tomoyo/realpath.c:284
Read of size 2 at addr ffff888091bcd4d0 by task syz-executor.4/10210

CPU: 0 PID: 10210 Comm: syz-executor.4 Not tainted 5.2.0-rc3+ #19
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_load2_noabort+0x14/0x20 mm/kasan/generic_report.c:130
 tomoyo_get_socket_name security/tomoyo/realpath.c:238 [inline]
 tomoyo_realpath_from_path+0x722/0x7a0 security/tomoyo/realpath.c:284
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_check_open_permission+0x2a8/0x3f0 security/tomoyo/file.c:771
 tomoyo_file_open security/tomoyo/tomoyo.c:319 [inline]
 tomoyo_file_open+0xa9/0xd0 security/tomoyo/tomoyo.c:314
 security_file_open+0x71/0x300 security/security.c:1454
 do_dentry_open+0x373/0x1250 fs/open.c:765
 vfs_open+0xa0/0xd0 fs/open.c:887
 do_last fs/namei.c:3416 [inline]
 path_openat+0x10e9/0x46d0 fs/namei.c:3533
 do_filp_open+0x1a1/0x280 fs/namei.c:3563
 do_sys_open+0x3fe/0x5d0 fs/open.c:1070
 __do_sys_open fs/open.c:1088 [inline]
 __se_sys_open fs/open.c:1083 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1083
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413161
Code: 75 14 b8 02 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 19 00 00 c3 48 83 ec 08 e8 0a fa ff ff 48 89 04 24 b8 02 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fa ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f84687abbb0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000413161
RDX: fffffffffffffffa RSI: 0000000000000000 RDI: 00007f84687abbd0
RBP: 000000000075bfc0 R08: 0000000000000050 R09: 000000000000000f
R10: 0000000000000004 R11: 0000000000000293 R12: 00007f84687ac6d4
R13: 00000000004c83f6 R14: 00000000004dea40 R15: 00000000ffffffff

Allocated by task 10203:
 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_kmalloc+0x9/0x10 mm/kasan/common.c:503
 __do_kmalloc mm/slab.c:3660 [inline]
 __kmalloc+0x15c/0x740 mm/slab.c:3669
 kmalloc include/linux/slab.h:552 [inline]
 sk_prot_alloc+0x19c/0x2e0 net/core/sock.c:1602
 sk_alloc+0x39/0xf70 net/core/sock.c:1656
 base_sock_create drivers/isdn/mISDN/socket.c:758 [inline]
 mISDN_sock_create+0xb4/0x3a0 drivers/isdn/mISDN/socket.c:780
 __sock_create+0x3d8/0x730 net/socket.c:1424
 sock_create net/socket.c:1475 [inline]
 __sys_socket+0x103/0x220 net/socket.c:1517
 __do_sys_socket net/socket.c:1526 [inline]
 __se_sys_socket net/socket.c:1524 [inline]
 __x64_sys_socket+0x73/0xb0 net/socket.c:1524
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 10202:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
 __cache_free mm/slab.c:3432 [inline]
 kfree+0xcf/0x220 mm/slab.c:3755
 sk_prot_free net/core/sock.c:1639 [inline]
 __sk_destruct+0x4f7/0x6e0 net/core/sock.c:1725
 sk_destruct+0x7b/0x90 net/core/sock.c:1733
 __sk_free+0xce/0x300 net/core/sock.c:1744
 sk_free+0x42/0x50 net/core/sock.c:1755
 sock_put include/net/sock.h:1723 [inline]
 base_sock_release+0x269/0x279 drivers/isdn/mISDN/socket.c:628
 __sock_release+0xce/0x2a0 net/socket.c:601
 sock_close+0x1b/0x30 net/socket.c:1273
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:185 [inline]
 exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888091bcd4c0
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 16 bytes inside of
 2048-byte region [ffff888091bcd4c0, ffff888091bcdcc0)
The buggy address belongs to the page:
page:ffffea000246f300 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea00024d6c88 ffffea000248d288 ffff8880aa400c40
raw: 0000000000000000 ffff888091bcc3c0 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888091bcd380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888091bcd400: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888091bcd480: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                 ^
 ffff888091bcd500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888091bcd580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/06/05 08:51 upstream 788a024921c4 bfb4a51e .config console log report syz ci-upstream-kasan-gce-smack-root
2019/06/05 07:04 upstream 788a024921c4 bfb4a51e .config console log report syz ci-upstream-kasan-gce-selinux-root
2019/06/14 16:35 linux-next f4788d37bc84 998ccc76 .config console log report syz ci-upstream-linux-next-kasan-gce-root
2019/12/16 04:01 upstream 07c4b9e9f71a eef6e580 .config console log report ci-upstream-kasan-gce
2019/10/24 04:34 upstream 13b86bc4cd64 b602d64b .config console log report ci-upstream-kasan-gce
2019/06/25 14:01 upstream 4b972a01a7da 82c13b6b .config console log report ci-upstream-kasan-gce
2019/09/12 02:21 linux-next 6d028043b55e f4e53c10 .config console log report ci-upstream-linux-next-kasan-gce-root
* Struck through repros no longer work on HEAD.