KASAN: use-after-free Write in __ext4_expand_extra

KASAN: use-after-free Write in __ext4_expand_extra_isize
Status: upstream: reported on 2019/07/23 02:57
Reported-by: syzbot+ae92ca7e152af41e7cf9@syzkaller.appspotmail.com
First crash: 114d, last: 3d07h

similar bugs (4):
Kernel	Title	Repro	Count	Last	Reported	Patched	Status
upstream	KASAN: use-after-free Write in __ext4_expand_extra_isize	C	95	199d	591d	13/14	fixed on 2019/06/14 18:22
linux-4.19	KASAN: use-after-free Write in __ext4_expand_extra_isize		6	5d00h	52d	0/1	upstream: reported on 2019/09/23 06:27
upstream	KASAN: use-after-free Write in __ext4_expand_extra_isize (2)		14	7d11h	24d	0/14	upstream: reported on 2019/10/21 05:23
android-414	KASAN: use-after-free Write in __ext4_expand_extra_isize		60	4d22h	215d	0/1	public: reported on 2019/04/13 00:01

Sample crash report:

EXT4-fs error (device sda1): ext4_xattr_set_entry:1605: inode #16531: comm syz-executor.1: corrupted xattr entries
EXT4-fs error (device sda1): ext4_xattr_set_entry:1605: inode #16530: comm syz-executor.1: corrupted xattr entries
==================================================================
BUG: KASAN: use-after-free in memset /./include/linux/string.h:332 [inline]
BUG: KASAN: use-after-free in __ext4_expand_extra_isize+0x14f/0x220 /fs/ext4/inode.c:5739
Write of size 2015 at addr ffff88808100cba0 by task syz-executor.5/7684

CPU: 0 PID: 7684 Comm: syz-executor.5 Not tainted 4.14.134 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack /lib/dump_stack.c:17 [inline]
 dump_stack+0x138/0x19c /lib/dump_stack.c:53
 print_address_description.cold+0x7c/0x1dc /mm/kasan/report.c:252
 kasan_report_error /mm/kasan/report.c:351 [inline]
 kasan_report /mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2af /mm/kasan/report.c:393
 check_memory_region_inline /mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x123/0x190 /mm/kasan/kasan.c:267
 memset+0x24/0x40 /mm/kasan/kasan.c:285
 memset /./include/linux/string.h:332 [inline]
 __ext4_expand_extra_isize+0x14f/0x220 /fs/ext4/inode.c:5739
 ext4_try_to_expand_extra_isize /fs/ext4/inode.c:5791 [inline]
 ext4_mark_inode_dirty+0x664/0x860 /fs/ext4/inode.c:5867
 ext4_ext_truncate+0x96/0x1f0 /fs/ext4/extents.c:4653
 ext4_truncate+0xbab/0x11f0 /fs/ext4/inode.c:4416
 ext4_evict_inode+0x8be/0x15c0 /fs/ext4/inode.c:288
 evict+0x2e6/0x630 /fs/inode.c:554
 iput_final /fs/inode.c:1516 [inline]
 iput /fs/inode.c:1543 [inline]
 iput+0x471/0x900 /fs/inode.c:1528
 dentry_unlink_inode+0x286/0x340 /fs/dcache.c:387
 __dentry_kill+0x32e/0x580 /fs/dcache.c:591
 dentry_kill /fs/dcache.c:632 [inline]
 dput.part.0+0x4e3/0x750 /fs/dcache.c:847
 dput+0x20/0x30 /fs/dcache.c:811
 path_put+0x31/0x70 /fs/namei.c:501
 free_fs_struct+0x25/0x70 /fs/fs_struct.c:90
 exit_fs+0xe7/0x120 /fs/fs_struct.c:107
 do_exit+0x7b9/0x2c10 /kernel/exit.c:870
 do_group_exit+0x111/0x330 /kernel/exit.c:977
 get_signal+0x381/0x1cd0 /kernel/signal.c:2409
 do_signal+0x86/0x19a0 /arch/x86/kernel/signal.c:814
 exit_to_usermode_loop+0x15c/0x220 /arch/x86/entry/common.c:160
 prepare_exit_to_usermode /arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath /arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4bc/0x640 /arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459829
RSP: 002b:00007f45aaa27cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000075bf28 RCX: 0000000000459829
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bf28
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c
R13: 00007ffdf05b432f R14: 00007f45aaa289c0 R15: 000000000075bf2c

The buggy address belongs to the page:
page:ffffea0002040300 count:2 mapcount:0 mapping:ffff888218421520 index:0x42b
flags: 0x1fffc0000001074(referenced|dirty|lru|active|private)
raw: 01fffc0000001074 ffff888218421520 000000000000042b 00000002ffffffff
raw: ffffea0001d8e920 ffffea000196f420 ffff888087702e70 ffff88821b7321c0
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88821b7321c0

Memory state around the buggy address:
 ffff88808100cf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88808100cf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88808100d000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88808100d080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88808100d100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (11):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Maintainers
ci2-linux-4-14	2019/07/23 01:56	linux-4.14.y	ff33472c	55e0c077	.config	log	report
ci2-linux-4-14	2019/11/11 14:12	linux-4.14.y	c9fda4f2	dc438b91	.config	log	report	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-linux-4-14	2019/10/19 15:26	linux-4.14.y	b98aebd2	8c88c9c1	.config	log	report	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-linux-4-14	2019/10/18 04:38	linux-4.14.y	b98aebd2	8c88c9c1	.config	log	report	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-linux-4-14	2019/10/14 03:27	linux-4.14.y	e132c8d7	2f661ec4	.config	log	report	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-linux-4-14	2019/10/04 22:52	linux-4.14.y	f6e27dbb	c86336cf	.config	log	report	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-linux-4-14	2019/10/02 09:09	linux-4.14.y	f6e27dbb	b7a87a83	.config	log	report	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-linux-4-14	2019/09/30 04:16	linux-4.14.y	f6e27dbb	c1ad5441	.config	log	report	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-linux-4-14	2019/09/15 16:52	linux-4.14.y	e2cd24b6	32d59357	.config	log	report	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-linux-4-14	2019/09/10 09:04	linux-4.14.y	414510bc	a60cb4cd	.config	log	report	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-linux-4-14	2019/09/04 03:06	linux-4.14.y	01fd1694	526709ff	.config	log	report	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu