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Date:   Wed, 31 Aug 2022 17:13:36 -0700
Message-ID: <000000000000117c7505e7927cb4@google.com>
Subject: [syzbot] UBSAN: array-index-out-of-bounds in truncate_inode_pages_range
From:   syzbot <syzbot+5867885efe39089b339b@syzkaller.appspotmail.com>
To:     akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        syzkaller-bugs@googlegroups.com, willy@infradead.org
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Hello,

syzbot found the following issue on:

HEAD commit:    89b749d8552d Merge tag 'fbdev-for-6.0-rc3' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14b9661b080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=911efaff115942bb
dashboard link: https://syzkaller.appspot.com/bug?extid=5867885efe39089b339b
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5867885efe39089b339b@syzkaller.appspotmail.com

ntfs3: loop0: Different NTFS' sector size (1024) and media sector size (512)
ntfs3: loop0: RAW NTFS volume: Filesystem size 0.00 Gb > volume size 0.00 Gb. Mount in read-only
================================================================================
UBSAN: array-index-out-of-bounds in mm/truncate.c:366:18
index 254 is out of range for type 'long unsigned int [15]'
CPU: 2 PID: 19915 Comm: syz-executor.0 Not tainted 6.0.0-rc2-syzkaller-00260-g89b749d8552d #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 ubsan_epilogue+0xb/0x50 lib/ubsan.c:151
 __ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:283
 truncate_inode_pages_range+0x12f4/0x1510 mm/truncate.c:366
 ntfs_evict_inode+0x16/0xa0 fs/ntfs3/inode.c:1741
 evict+0x2ed/0x6b0 fs/inode.c:665
 iput_final fs/inode.c:1748 [inline]
 iput.part.0+0x55d/0x810 fs/inode.c:1774
 iput+0x58/0x70 fs/inode.c:1764
 ntfs_fill_super+0x2e89/0x37f0 fs/ntfs3/super.c:1190
 get_tree_bdev+0x440/0x760 fs/super.c:1323
 vfs_get_tree+0x89/0x2f0 fs/super.c:1530
 do_new_mount fs/namespace.c:3040 [inline]
 path_mount+0x1326/0x1e20 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __ia32_sys_mount+0x27e/0x300 fs/namespace.c:3568
 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
 __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203
 entry_SYSENTER_compat_after_hwframe+0x70/0x82
RIP: 0023:0xf7ff6549
Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f7ff1410 EFLAGS: 00000296 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 00000000f7ff1480 RCX: 0000000020000100
RDX: 0000000020000000 RSI: 0000000000000000 RDI: 00000000f7ff14c0
RBP: 00000000f7ff14c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
================================================================================
----------------
Code disassembly (best guess):
   0:	03 74 c0 01          	add    0x1(%rax,%rax,8),%esi
   4:	10 05 03 74 b8 01    	adc    %al,0x1b87403(%rip)        # 0x1b8740d
   a:	10 06                	adc    %al,(%rsi)
   c:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
  10:	10 07                	adc    %al,(%rdi)
  12:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
  16:	10 08                	adc    %cl,(%rax)
  18:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1c:	00 00                	add    %al,(%rax)
  1e:	00 00                	add    %al,(%rax)
  20:	00 51 52             	add    %dl,0x52(%rcx)
  23:	55                   	push   %rbp
  24:	89 e5                	mov    %esp,%ebp
  26:	0f 34                	sysenter
  28:	cd 80                	int    $0x80
* 2a:	5d                   	pop    %rbp <-- trapping instruction
  2b:	5a                   	pop    %rdx
  2c:	59                   	pop    %rcx
  2d:	c3                   	retq
  2e:	90                   	nop
  2f:	90                   	nop
  30:	90                   	nop
  31:	90                   	nop
  32:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  39:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi


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