[syzbot] general protection fault in ext4_fill_super

From: syzbot <syzbot+138c9e58e3cb22eae3b4@syzkaller.appspotmail.com>
To: adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org,
	 linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
	nathan@kernel.org,  ndesaulniers@google.com,
	syzkaller-bugs@googlegroups.com, tytso@mit.edu
Subject: [syzbot] general protection fault in ext4_fill_super
Date: Mon, 17 Jan 2022 00:23:30 -0800	[thread overview]
Message-ID: <0000000000001e0ba105d5c2dede@google.com> (raw)

Hello,

syzbot found the following issue on:

HEAD commit:    daadb3bd0e8d Merge tag 'locking_core_for_v5.17_rc1' of git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=122fc6f7b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ec2807b2e9360dbb
dashboard link: https://syzkaller.appspot.com/bug?extid=138c9e58e3cb22eae3b4
compiler:       Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2

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+138c9e58e3cb22eae3b4@syzkaller.appspotmail.com

RBP: 00007f283db0b1d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007fffb1b01d5f R14: 00007f283db0b300 R15: 0000000000022000
 </TASK>
general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097]
CPU: 0 PID: 32175 Comm: syz-executor.3 Not tainted 5.16.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ext4_fill_super+0x240/0x770 fs/ext4/super.c:5551
Code: 3b 4c 89 6c 24 20 49 8d bd a8 06 00 00 be 2f 00 00 00 ba 21 00 00 00 e8 5e 6d d8 01 4d 8d af 90 00 00 00 4d 89 ec 49 c1 ec 03 <41> 80 3c 2c 00 74 08 4c 89 ef e8 11 4e 97 ff 49 c7 45 00 01 00 00
RSP: 0018:ffffc9000b5cfbe8 EFLAGS: 00010206
RAX: ffff8880234c46ac RBX: ffff888090bc7cf0 RCX: 0000000000040000
RDX: ffffc9000abd9000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: dffffc0000000000 R08: ffffffff8411122e R09: fffffbfff197f727
R10: fffffbfff197f727 R11: 0000000000000000 R12: 0000000000000012
R13: 0000000000000090 R14: ffff888071347b00 R15: 0000000000000000
FS:  00007f283db0b700(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6db90cb558 CR3: 000000008fafc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 get_tree_bdev+0x406/0x630 fs/super.c:1295
 vfs_get_tree+0x86/0x270 fs/super.c:1500
 do_new_mount fs/namespace.c:2994 [inline]
 path_mount+0x1986/0x2c30 fs/namespace.c:3324
 do_mount fs/namespace.c:3337 [inline]
 __do_sys_mount fs/namespace.c:3545 [inline]
 __se_sys_mount+0x308/0x3c0 fs/namespace.c:3522
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f283f195eb9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f283db0b168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f283f2a8f60 RCX: 00007f283f195eb9
RDX: 0000000020000240 RSI: 0000000020000000 RDI: 0000000020000100
RBP: 00007f283db0b1d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007fffb1b01d5f R14: 00007f283db0b300 R15: 0000000000022000
 </TASK>
Modules linked in:
---[ end trace 2017ba6e0452af99 ]---
RIP: 0010:ext4_fill_super+0x240/0x770 fs/ext4/super.c:5551
Code: 3b 4c 89 6c 24 20 49 8d bd a8 06 00 00 be 2f 00 00 00 ba 21 00 00 00 e8 5e 6d d8 01 4d 8d af 90 00 00 00 4d 89 ec 49 c1 ec 03 <41> 80 3c 2c 00 74 08 4c 89 ef e8 11 4e 97 ff 49 c7 45 00 01 00 00
RSP: 0018:ffffc9000b5cfbe8 EFLAGS: 00010206
RAX: ffff8880234c46ac RBX: ffff888090bc7cf0 RCX: 0000000000040000
RDX: ffffc9000abd9000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: dffffc0000000000 R08: ffffffff8411122e R09: fffffbfff197f727
R10: fffffbfff197f727 R11: 0000000000000000 R12: 0000000000000012
R13: 0000000000000090 R14: ffff888071347b00 R15: 0000000000000000
FS:  00007f283db0b700(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8eb615a718 CR3: 000000008fafc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	3b 4c 89 6c          	cmp    0x6c(%rcx,%rcx,4),%ecx
   4:	24 20                	and    $0x20,%al
   6:	49 8d bd a8 06 00 00 	lea    0x6a8(%r13),%rdi
   d:	be 2f 00 00 00       	mov    $0x2f,%esi
  12:	ba 21 00 00 00       	mov    $0x21,%edx
  17:	e8 5e 6d d8 01       	callq  0x1d86d7a
  1c:	4d 8d af 90 00 00 00 	lea    0x90(%r15),%r13
  23:	4d 89 ec             	mov    %r13,%r12
  26:	49 c1 ec 03          	shr    $0x3,%r12
* 2a:	41 80 3c 2c 00       	cmpb   $0x0,(%r12,%rbp,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 ef             	mov    %r13,%rdi
  34:	e8 11 4e 97 ff       	callq  0xff974e4a
  39:	49                   	rex.WB
  3a:	c7                   	.byte 0xc7
  3b:	45 00 01             	add    %r8b,(%r9)

---
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