KASAN: use-after-free Write in __ext4_expand_extra_isize (2)

Status: fixed on 2019/12/13 00:31
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+44b6763edfc17144296f@syzkaller.appspotmail.com
Fix commit: 4ea99936a163 ext4: add more paranoia checking in ext4_expand_extra_isize handling
First crash: 2598d, last: 2453d
▶ ▼ Duplicate bugs (1)
Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
KASAN: use-after-free Write in ext4_mark_inode_dirty ext4 22 5 2457d 2431d 0/29 closed as dup on 2019/11/29 12:55
▶ ▼ Discussions (9)
Title Replies (including bot) Last reply
[PATCH 4.19 000/321] 4.19.88-stable review 352 (352) 2020/02/09 12:41
[PATCH 4.4 00/76] 4.4.211-stable review 81 (81) 2020/01/22 20:52
[PATCH 4.9 00/97] 4.9.211-stable review 102 (102) 2020/01/22 20:52
[PATCH 3.16 00/63] 3.16.81-rc1 review 68 (68) 2020/01/10 16:01
[PATCH 4.14 000/209] 4.14.158-stable review 223 (223) 2019/12/10 00:52
[PATCH 5.4 00/46] 5.4.2-stable review 58 (58) 2019/12/06 13:05
[PATCH 5.3 000/135] 5.3.15-stable review 140 (140) 2019/12/04 19:13
[PATCH] ext4: add more paranoia checking in ext4_expand_extra_isize handling 6 (6) 2019/11/19 04:36
KASAN: use-after-free Write in __ext4_expand_extra_isize (2) 0 (1) 2019/10/21 05:23
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 KASAN: use-after-free Write in __ext4_expand_extra_isize 22 11 2449d 2561d 0/1 auto-closed as invalid on 2020/03/10 14:13
upstream KASAN: use-after-free Write in __ext4_expand_extra_isize ext4 22 C 95 2646d 3037d 12/29 fixed on 2019/06/14 18:22
linux-4.19 KASAN: use-after-free Write in __ext4_expand_extra_isize 22 7 2437d 2498d 0/1 auto-closed as invalid on 2020/03/22 21:28
android-414 KASAN: use-after-free Write in __ext4_expand_extra_isize 22 65 2429d 2662d 0/1 auto-closed as invalid on 2020/03/31 02:59

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in memset include/linux/string.h:363 [inline]
BUG: KASAN: use-after-free in __ext4_expand_extra_isize+0x1ab/0x290 fs/ext4/inode.c:5924
Write of size 4063 at addr ffff8880554ff0a0 by task syz-executor.0/9247

CPU: 0 PID: 9247 Comm: syz-executor.0 Not tainted 5.4.0-rc5+ #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+0x172/0x1f0 lib/dump_stack.c:113
 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:634
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x134/0x1a0 mm/kasan/generic.c:192
 memset+0x24/0x40 mm/kasan/common.c:105
 memset include/linux/string.h:363 [inline]
 __ext4_expand_extra_isize+0x1ab/0x290 fs/ext4/inode.c:5924
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5976 [inline]
 ext4_mark_inode_dirty+0x74e/0x9b0 fs/ext4/inode.c:6052
 ext4_unlink fs/ext4/namei.c:3195 [inline]
 ext4_unlink+0xce6/0x10e0 fs/ext4/namei.c:3140
 vfs_unlink+0x2d7/0x620 fs/namei.c:3991
 do_unlinkat+0x3f7/0x6d0 fs/namei.c:4055
 __do_sys_unlink fs/namei.c:4102 [inline]
 __se_sys_unlink fs/namei.c:4100 [inline]
 __x64_sys_unlink+0x42/0x50 fs/namei.c:4100
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459c97
Code: 00 66 90 b8 58 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 4d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 2d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd984b5b18 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000459c97
RDX: 00007ffd984b5b30 RSI: 00007ffd984b5b30 RDI: 00007ffd984b5bc0
RBP: 0000000000000b2b R08: 0000000000000000 R09: 0000000000000010
R10: 000000000000000a R11: 0000000000000246 R12: 00007ffd984b6c50
R13: 0000000002228940 R14: 0000000000000000 R15: 00007ffd984b6c50

The buggy address belongs to the page:
page:ffffea0001553fc0 refcount:2 mapcount:0 mapping:ffff888219f11ae0 index:0x42e
def_blk_aops 
flags: 0x1fffc000000203a(referenced|dirty|lru|active|private)
raw: 01fffc000000203a ffffea00018288c8 ffffea0001554a48 ffff888219f11ae0
raw: 000000000000042e ffff8880aa09fe70 00000002ffffffff ffff888057a32000
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888057a32000

Memory state around the buggy address:
 ffff8880554fff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880554fff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888055500000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888055500080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888055500100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/11/03 07:23 upstream 9d2345057538 a41ca8fa .config console log report ci-upstream-kasan-gce-selinux-root
2019/10/29 09:51 upstream 8005803a2ca0 5ea87a66 .config console log report ci-upstream-kasan-gce-root
2019/10/28 22:05 upstream 9e5eefba3d09 439d7b14 .config console log report ci-upstream-kasan-gce-root
2019/10/05 08:19 upstream b145b0eb2031 f3f7d9c8 .config console log report ci-upstream-kasan-gce-selinux-root
2019/09/26 00:21 upstream f41def397161 a3355dba .config console log report ci-upstream-kasan-gce-root
2019/09/08 21:03 upstream 950b07c14e8c a60cb4cd .config console log report ci-upstream-kasan-gce-root
2019/08/27 16:12 upstream a55aa89aab90 d21c5d9d .config console log report ci-upstream-kasan-gce-selinux-root
2019/08/16 18:00 upstream a69e90512d9d 8fd428a1 .config console log report ci-upstream-kasan-gce-root
2019/06/21 00:37 upstream abf02e2964b3 34bf9440 .config console log report ci-upstream-kasan-gce-root
2019/11/07 11:08 linux-next c68c5373c504 d797d201 .config console log report ci-upstream-linux-next-kasan-gce-root
2019/10/05 08:45 linux-next 311ef88adfa3 f3f7d9c8 .config console log report ci-upstream-linux-next-kasan-gce-root
2019/09/23 05:27 linux-next b5b3bd898ba9 d96e88f3 .config console log report ci-upstream-linux-next-kasan-gce-root
2019/09/10 05:32 linux-next 6d028043b55e a60cb4cd .config console log report ci-upstream-linux-next-kasan-gce-root
2019/06/15 08:09 linux-next f4788d37bc84 442206d7 .config console log report ci-upstream-linux-next-kasan-gce-root
* Struck through repros no longer work on HEAD.