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KASAN: slab-out-of-bounds Write in record_print_text

Status: fixed on 2021/03/10 01:48
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+a42d84593d6a89a76f26@syzkaller.appspotmail.com
Fix commit: 08d60e599954 printk: fix string termination for record_print_text()
First crash: 1191d, last: 1184d
Cause bisection: introduced by (bisect log) :
commit f0e386ee0c0b71ea6f7238506a4d0965a2dbef11
Author: John Ogness <john.ogness@linutronix.de>
Date: Thu Jan 14 17:04:12 2021 +0000

  printk: fix buffer overflow potential for print_text()

Crash: INFO: trying to register non-static key in ipv6_get_lladdr (log)
Repro: C syz .config
  
Fix bisection: fixed by (bisect log) [no-op commit]:
commit 38d26b244367e84ed657ac4f5093ae9e71c8a7a2
Author: Michael Walle <michael@walle.cc>
Date: Mon Dec 28 13:00:31 2020 +0000

  enetc: drop unneeded indirection

  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
KASAN: slab-out-of-bounds Write in record_print_text 2 (3) 2021/03/09 14:14
▶ ▼ Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: global-out-of-bounds Write in record_print_text kernel C done unreliable 45 1186d 1187d 0/26 auto-obsoleted due to no activity on 2023/04/16 08:59

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in record_print_text+0x33f/0x380 kernel/printk/printk.c:1401
Write of size 1 at addr ffff888027e5d764 by task in:imklog/8158

CPU: 1 PID: 8158 Comm: in:imklog Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2c6 mm/kasan/report.c:230
 __kasan_report mm/kasan/report.c:396 [inline]
 kasan_report.cold+0x79/0xd5 mm/kasan/report.c:413
 record_print_text+0x33f/0x380 kernel/printk/printk.c:1401
 syslog_print+0x2bb/0x430 kernel/printk/printk.c:1459
 do_syslog.part.0+0x2a8/0x7c0 kernel/printk/printk.c:1586
 do_syslog+0x49/0x60 kernel/printk/printk.c:1567
 kmsg_read+0x90/0xb0 fs/proc/kmsg.c:40
 pde_read fs/proc/inode.c:321 [inline]
 proc_reg_read+0x119/0x300 fs/proc/inode.c:331
 vfs_read+0x1b5/0x570 fs/read_write.c:494
 ksys_read+0x12d/0x250 fs/read_write.c:634
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fe0e808f22d
Code: c1 20 00 00 75 10 b8 00 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 4e fc ff ff 48 89 04 24 b8 00 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 97 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fe0e5a2b580 EFLAGS: 00000293 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe0e808f22d
RDX: 0000000000001fa0 RSI: 00007fe0e5a2bda0 RDI: 0000000000000004
RBP: 00005572425759d0 R08: 0000000000000000 R09: 0000000004000001
R10: 0000000000000001 R11: 0000000000000293 R12: 00007fe0e5a2bda0
R13: 0000000000001fa0 R14: 0000000000001f9f R15: 00007fe0e5a2be04

Allocated by task 8158:
 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:401 [inline]
 ____kasan_kmalloc.constprop.0+0x7f/0xa0 mm/kasan/common.c:429
 kasan_kmalloc include/linux/kasan.h:219 [inline]
 kmem_cache_alloc_trace+0x1e0/0x400 mm/slab.c:3554
 kmalloc include/linux/slab.h:552 [inline]
 syslog_print+0xb2/0x430 kernel/printk/printk.c:1430
 do_syslog.part.0+0x2a8/0x7c0 kernel/printk/printk.c:1586
 do_syslog+0x49/0x60 kernel/printk/printk.c:1567
 kmsg_read+0x90/0xb0 fs/proc/kmsg.c:40
 pde_read fs/proc/inode.c:321 [inline]
 proc_reg_read+0x119/0x300 fs/proc/inode.c:331
 vfs_read+0x1b5/0x570 fs/read_write.c:494
 ksys_read+0x12d/0x250 fs/read_write.c:634
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888027e5d000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 868 bytes to the right of
 1024-byte region [ffff888027e5d000, ffff888027e5d400)
The buggy address belongs to the page:
page:000000004be8ec80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x27e5d
flags: 0xfff00000000200(slab)
raw: 00fff00000000200 ffffea00009f9708 ffff888010041850 ffff888010040700
raw: 0000000000000000 ffff888027e5d000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888027e5d600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888027e5d680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888027e5d700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                       ^
 ffff888027e5d780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888027e5d800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (17):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/01/25 04:50 upstream e68061375f79 52e37319 .config console log report syz C ci-upstream-kasan-gce-selinux-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/25 04:39 upstream e68061375f79 52e37319 .config console log report syz C ci-upstream-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/25 04:41 linux-next bc085f8fc88f 52e37319 .config console log report syz C ci-upstream-linux-next-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/25 04:12 upstream e68061375f79 52e37319 .config console log report info ci-upstream-kasan-gce-selinux-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/25 04:10 upstream e68061375f79 52e37319 .config console log report info ci-upstream-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/25 04:09 upstream e68061375f79 52e37319 .config console log report info ci-upstream-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/23 00:43 upstream 83d09ad4b950 4080af96 .config console log report info ci-upstream-kasan-gce-selinux-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/23 00:31 upstream 83d09ad4b950 4080af96 .config console log report info ci-upstream-kasan-gce-selinux-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/22 03:34 upstream 9f29bd8b2e71 d4f4eca5 .config console log report info ci-upstream-kasan-gce-386 KASAN: slab-out-of-bounds Write in record_print_text
2021/01/28 07:40 linux-next bc085f8fc88f eefc07f2 .config console log report info ci-upstream-linux-next-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/28 04:15 linux-next bc085f8fc88f eefc07f2 .config console log report info ci-upstream-linux-next-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/26 11:10 linux-next bc085f8fc88f 52e37319 .config console log report info ci-upstream-linux-next-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/26 11:05 linux-next bc085f8fc88f 52e37319 .config console log report info ci-upstream-linux-next-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/26 10:30 linux-next bc085f8fc88f 52e37319 .config console log report info ci-upstream-linux-next-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/26 07:21 linux-next bc085f8fc88f 52e37319 .config console log report info ci-upstream-linux-next-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/25 04:09 linux-next bc085f8fc88f 52e37319 .config console log report info ci-upstream-linux-next-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
2021/01/25 04:09 linux-next bc085f8fc88f 52e37319 .config console log report info ci-upstream-linux-next-kasan-gce-root KASAN: slab-out-of-bounds Write in record_print_text
* Struck through repros no longer work on HEAD.