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

Status: fixed on 2020/01/08 01:06
Reported-by: syzbot+838eb0878ffd51f27c41@syzkaller.appspotmail.com
Fix commit: 8f868d68d335 pipe: Fix missing mask update after pipe_wait()
First crash: 2168d, last: 2162d
Cause bisection: introduced by (bisect log) :
commit a194dfe6e6f6f7205eea850a420f2bc6a1541209
Author: David Howells <dhowells@redhat.com>
Date: Fri Sep 20 15:32:19 2019 +0000

  pipe: Rearrange sequence in pipe_write() to preallocate slot

Crash: KASAN: slab-out-of-bounds Write in pipe_write (log)
Repro: C syz .config
  
▶ ▼ Discussions (3)
Title Replies (including bot) Last reply
[PATCH 0/2] pipe: Fixes [ver #2] 41 (41) 2019/12/19 16:35
[PATCH 0/2] pipe: Fixes 5 (5) 2019/12/05 17:42
KASAN: slab-out-of-bounds Write in pipe_write 2 (4) 2019/12/05 16:33

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in pipe_write+0xe30/0x1000 fs/pipe.c:488
Write of size 8 at addr ffff88809ae61aa8 by task syz-executor462/9998

CPU: 0 PID: 9998 Comm: syz-executor462 Not tainted 5.4.0-syzkaller #0
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+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:638
 __asan_report_store8_noabort+0x17/0x20 mm/kasan/generic_report.c:140
 pipe_write+0xe30/0x1000 fs/pipe.c:488
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write+0x4d3/0x770 fs/read_write.c:483
 __vfs_write+0xe1/0x110 fs/read_write.c:496
 vfs_write+0x268/0x5d0 fs/read_write.c:558
 ksys_write+0x220/0x290 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:620
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445879
Code: e8 ec bc 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 cb 11 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1adc8a8db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000006dac28 RCX: 0000000000445879
RDX: 00000000fffffef3 RSI: 00000000200001c0 RDI: 0000000000000004
RBP: 00000000006dac20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac2c
R13: 00007fff303618ef R14: 00007f1adc8a99c0 R15: 0000000000000000

Allocated by task 10000:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:512 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:485
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:526
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x163/0x770 mm/slab.c:3665
 kmalloc_array include/linux/slab.h:598 [inline]
 kcalloc include/linux/slab.h:609 [inline]
 pipe_set_size fs/pipe.c:1143 [inline]
 pipe_fcntl+0x3f7/0x8e0 fs/pipe.c:1209
 do_fcntl+0x255/0x1030 fs/fcntl.c:417
 __do_sys_fcntl fs/fcntl.c:463 [inline]
 __se_sys_fcntl fs/fcntl.c:448 [inline]
 __x64_sys_fcntl+0x16d/0x1e0 fs/fcntl.c:448
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff88809ae61a80
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 40 bytes inside of
 64-byte region [ffff88809ae61a80, ffff88809ae61ac0)
The buggy address belongs to the page:
page:ffffea00026b9840 refcount:1 mapcount:0 mapping:ffff8880aa400380 index:0x0
raw: 00fffe0000000200 ffffea00029f2fc8 ffff8880aa401348 ffff8880aa400380
raw: 0000000000000000 ffff88809ae61000 0000000100000020 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809ae61980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809ae61a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809ae61a80: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
                                  ^
 ffff88809ae61b00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88809ae61b80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================

Crashes (40):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/12/03 06:11 upstream 596cf45cbf6e ab342da3 .config console log report syz C ci-upstream-kasan-gce-selinux-root
2019/12/03 05:49 upstream 596cf45cbf6e ab342da3 .config console log report syz C ci-upstream-kasan-gce-selinux-root
2019/12/03 05:28 upstream 596cf45cbf6e ab342da3 .config console log report syz C ci-upstream-kasan-gce-selinux-root
2019/12/03 04:25 upstream 596cf45cbf6e ab342da3 .config console log report syz C ci-upstream-kasan-gce-root
2019/12/03 04:04 upstream 596cf45cbf6e ab342da3 .config console log report syz C ci-upstream-kasan-gce-root
2019/12/03 03:46 upstream 596cf45cbf6e ab342da3 .config console log report syz C ci-upstream-kasan-gce-root
2019/12/03 03:05 upstream 596cf45cbf6e ab342da3 .config console log report syz C ci-upstream-kasan-gce-root
2019/12/02 10:05 upstream ceb307474506 f879db37 .config console log report syz C ci-upstream-kasan-gce
2019/12/02 09:05 upstream ceb307474506 f879db37 .config console log report syz C ci-upstream-kasan-gce
2019/12/02 04:21 upstream b94ae8ad9fe7 f879db37 .config console log report syz C ci-upstream-kasan-gce-smack-root
2019/12/02 04:00 upstream b94ae8ad9fe7 f879db37 .config console log report syz C ci-upstream-kasan-gce
2019/12/02 03:49 upstream b94ae8ad9fe7 f879db37 .config console log report syz C ci-upstream-kasan-gce-selinux-root
2019/12/02 11:26 upstream ceb307474506 f879db37 .config console log report syz C ci-upstream-kasan-gce-386
2019/12/02 05:26 upstream b94ae8ad9fe7 f879db37 .config console log report syz C ci-upstream-kasan-gce-386
2019/12/02 04:04 upstream b94ae8ad9fe7 f879db37 .config console log report syz C ci-upstream-kasan-gce-386
2019/12/05 22:43 upstream 2f13437b8917 4fb74474 .config console log report syz ci-upstream-kasan-gce-root
2019/12/05 20:28 upstream 2f13437b8917 4fb74474 .config console log report syz ci-upstream-kasan-gce-selinux-root
2019/12/02 09:50 upstream ceb307474506 f879db37 .config console log report syz ci-upstream-kasan-gce-root
2019/12/02 09:39 upstream ceb307474506 f879db37 .config console log report syz ci-upstream-kasan-gce
2019/12/02 03:01 upstream b94ae8ad9fe7 f879db37 .config console log report syz ci-upstream-kasan-gce-selinux-root
2019/12/01 22:11 upstream b94ae8ad9fe7 a76bf83f .config console log report syz ci-upstream-kasan-gce
2019/12/02 11:00 upstream ceb307474506 f879db37 .config console log report syz ci-upstream-kasan-gce-386
2019/12/06 08:14 upstream 0f137416247f 98b4ef2d .config console log report ci-qemu-upstream
2019/12/05 14:13 upstream 2f13437b8917 4fb74474 .config console log report ci-upstream-kasan-gce-selinux-root
2019/12/05 01:52 upstream 63de37476ebd b2088328 .config console log report ci-upstream-kasan-gce-root
2019/12/04 20:07 upstream aedc0650f913 b2088328 .config console log report ci-qemu-upstream
2019/12/04 14:13 upstream 63de37476ebd b2088328 .config console log report ci-upstream-kasan-gce-selinux-root
2019/12/03 19:10 upstream 76bb8b05960c ae13a849 .config console log report ci-upstream-kasan-gce-root
2019/12/02 05:59 upstream ceb307474506 f879db37 .config console log report ci-qemu-upstream
2019/12/02 03:21 upstream b94ae8ad9fe7 f879db37 .config console log report ci-upstream-kasan-gce-selinux-root
2019/12/02 03:21 upstream b94ae8ad9fe7 f879db37 .config console log report ci-upstream-kasan-gce-smack-root
2019/12/02 03:19 upstream b94ae8ad9fe7 f879db37 .config console log report ci-upstream-kasan-gce-smack-root
2019/12/02 03:18 upstream ceb307474506 f879db37 .config console log report ci-qemu-upstream
2019/12/02 03:18 upstream b94ae8ad9fe7 f879db37 .config console log report ci-upstream-kasan-gce
2019/12/02 03:18 upstream ceb307474506 f879db37 .config console log report ci-qemu-upstream
2019/12/02 01:18 upstream b94ae8ad9fe7 f879db37 .config console log report ci-upstream-kasan-gce-selinux-root
2019/12/01 18:24 upstream b94ae8ad9fe7 a76bf83f .config console log report ci-upstream-kasan-gce
2019/12/02 03:27 upstream b94ae8ad9fe7 f879db37 .config console log report ci-upstream-kasan-gce-386
2019/12/07 09:51 linux-next 838333c80c4f 85f26751 .config console log report ci-upstream-linux-next-kasan-gce-root
2019/12/06 10:43 linux-next 838333c80c4f 98b4ef2d .config console log report ci-upstream-linux-next-kasan-gce-root
* Struck through repros no longer work on HEAD.