Message-ID: <BL0PR11MB31066DF3F30927A7F82F22FEE1EEA@BL0PR11MB3106.namprd11.prod.outlook.com>
Date:   Tue, 12 Sep 2023 23:02:35 +0000
From:   Sanan Hasanov <Sanan.Hasanov@....edu>
To:     "tytso@....edu" <tytso@....edu>,
        "adilger.kernel@...ger.ca" <adilger.kernel@...ger.ca>,
        "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "syzkaller@...glegroups.com" <syzkaller@...glegroups.com>,
        "contact@...zz.com" <contact@...zz.com>
Subject: general protection fault in ext4_update_overhead

Good day, dear maintainers,

We found a bug using a modified kernel configuration file used by syzbot.

We enhanced the coverage of the configuration file using our tool, klocalizer.

Kernel Branch: 6.3.0-next-20230426
Kernel Config: https://drive.google.com/file/d/1xpe7qMUUYvHQFzqZGUzcco9jF97EwTqQ/view?usp=sharing
Reproducer: https://drive.google.com/file/d/1Q8ix6EiWrzx0bWLyoGTHP721KE4Ei3qf/view?usp=sharing
Thank you!

Best regards,
Sanan Hasanov

general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
kobject: 'loop6' (00000000df72f20a): kobject_uevent_env
CPU: 2 PID: 20787 Comm: syz-executor.4 Not tainted 6.3.0-next-20230426 #1
kobject: 'loop6' (00000000df72f20a): fill_kobj_path: path = '/devices/virtual/block/loop6'
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:ext4_update_overhead+0xb3/0x1a0
Code: 00 00 e8 20 cd 57 ff 45 84 ed 0f 85 b1 00 00 00 e8 62 d2 57 ff 4c 8d 73 48 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 c8 00 00 00 4c 8b 6b 48 31 ff 4c 89 ee e8 95 cd
RSP: 0018:ffff88801d51fac8 EFLAGS: 00010216
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000009 RSI: ffffffff823198fe RDI: ffffffff823198f0
RBP: ffff88801d51fae8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff8880516be000
R13: 0000000000000000 R14: 0000000000000048 R15: ffff8880516be000
FS:  00007f442e80f700(0000) GS:ffff88811a300000(0000) knlGS:0000000000000000
kobject: 'loop1' (00000000f3e7cad3): kobject_uevent_env
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kobject: 'loop1' (00000000f3e7cad3): fill_kobj_path: path = '/devices/virtual/block/loop1'
CR2: 0000555555bfdc88 CR3: 0000000050354000 CR4: 0000000000350ee0
Call Trace:
 <TASK>
 ext4_fill_super+0x30c8/0xb8d0
 get_tree_bdev+0x447/0x770
 ext4_get_tree+0x21/0x30
 vfs_get_tree+0x97/0x370
 path_mount+0x6d3/0x1fb0
 __x64_sys_mount+0x2b2/0x340
 do_syscall_64+0x3f/0x90
 entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7f442d69176e
Code: 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f442e80ea08 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 00007f442d69176e
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f442e80ea60
RBP: 00007f442e80eaa0 R08: 00007f442e80eaa0 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000020000000
R13: 0000000020000100 R14: 00007f442e80ea60 R15: 00000000200008c0
 </TASK>
Modules linked in:
kobject: 'loop2' (0000000027c67f3b): kobject_uevent_env
kobject: 'loop2' (0000000027c67f3b): fill_kobj_path: path = '/devices/virtual/block/loop2'
---[ end trace 0000000000000000 ]---
kobject: 'loop2' (0000000027c67f3b): kobject_uevent_env
RIP: 0010:ext4_update_overhead+0xb3/0x1a0
kobject: 'loop2' (0000000027c67f3b): fill_kobj_path: path = '/devices/virtual/block/loop2'
Code: 00 00 e8 20 cd 57 ff 45 84 ed 0f 85 b1 00 00 00 e8 62 d2 57 ff 4c 8d 73 48 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 c8 00 00 00 4c 8b 6b 48 31 ff 4c 89 ee e8 95 cd
RSP: 0018:ffff88801d51fac8 EFLAGS: 00010216
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000009 RSI: ffffffff823198fe RDI: ffffffff823198f0
RBP: ffff88801d51fae8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff8880516be000
R13: 0000000000000000 R14: 0000000000000048 R15: ffff8880516be000
kobject: 'loop2' (0000000027c67f3b): kobject_uevent_env
FS:  00007f442e80f700(0000) GS:ffff88811a300000(0000) knlGS:0000000000000000
kobject: 'loop2' (0000000027c67f3b): kobject_uevent_env: uevent_suppress caused the event to drop!
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kobject: 'loop2' (0000000027c67f3b): kobject_uevent_env
kobject: 'loop2' (0000000027c67f3b): kobject_uevent_env: uevent_suppress caused the event to drop!
loop2: detected capacity change from 0 to 64
CR2: 00007f42967bd0b0 CR3: 0000000050354000 CR4: 0000000000350ee0
kobject: 'loop2' (0000000027c67f3b): kobject_uevent_env
----------------
Code disassembly (best guess):
   0:   00 00                   add    %al,(%rax)
   2:   e8 20 cd 57 ff          call   0xff57cd27
   7:   45 84 ed                test   %r13b,%r13b
   a:   0f 85 b1 00 00 00       jne    0xc1
  10:   e8 62 d2 57 ff          call   0xff57d277
  15:   4c 8d 73 48             lea    0x48(%rbx),%r14
  19:   48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
  20:   fc ff df
  23:   4c 89 f2                mov    %r14,%rdx
  26:   48 c1 ea 03             shr    $0x3,%rdx
* 2a:   80 3c 02 00             cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:   0f 85 c8 00 00 00       jne    0xfc
  34:   4c 8b 6b 48             mov    0x48(%rbx),%r13
  38:   31 ff                   xor    %edi,%edi
  3a:   4c 89 ee                mov    %r13,%rsi
  3d:   e8                      .byte 0xe8
  3e:   95                      xchg   %eax,%ebp
  3f:   cd                      .byte 0xcd

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