Re: BUG: unable to handle kernel NULL pointer dereference in gfs2_evict_inode

[Dmitry Vyukov]

On Fri, 18 Nov 2022 at 09:06, Wei Chen <harperchen1110@xxxxxxxxx> wrote:
>
> Dear Linux developers,
>
> The bug persists in upstream Linux v6.0-rc5.

If you fix this, please also add the syzbot tag:

Reported-by: syzbot+8a5fc6416c175cecea34@xxxxxxxxxxxxxxxxxxxxxxxxx
https://lore.kernel.org/all/000000000000ab092305e268a016@xxxxxxxxxx/

> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000020000000
> R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020047a20
>  </TASK>
> gfs2: fsid=syz:syz.0: can't read journal index: -5
> BUG: kernel NULL pointer dereference, address: 0000000000000064
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 28908067 P4D 28908067 PUD 28909067 PMD 0
> Oops: 0000 [#1] PREEMPT SMP
> CPU: 0 PID: 14812 Comm: syz-executor.1 Not tainted
> 6.1.0-rc5-63183-gd418a331631b #1
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> Ubuntu-1.8.2-1ubuntu1 04/01/2014
> RIP: 0010:evict_linked_inode fs/gfs2/super.c:1330 [inline]
> RIP: 0010:gfs2_evict_inode+0x449/0xb70 fs/gfs2/super.c:1385
> Code: 00 00 00 48 89 df e8 46 13 5a ff 48 8b bb a8 02 00 00 31 f6 e8
> d8 70 fd ff 48 8b 4c 24 20 31 f6 48 8b 81 b0 05 00 00 48 89 cf <8b> 50
> 64 e8 5f 4b 00 00 31 ff 41 89 c7 89 c6 e8 e3 86 2d ff 45 85
> RSP: 0018:ffff88802aec3a80 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: ffff88800eb70f00 RCX: ffff888028c58000
> RDX: ffffc900092dc000 RSI: 0000000000000000 RDI: ffff888028c58000
> RBP: ffff88802aec3b38 R08: ffffffff81fb50c2 R09: 0000000000000000
> R10: 0000000000000005 R11: 0000000000000000 R12: ffff88800eb71228
> R13: ffff88800eb71078 R14: ffff888028c58000 R15: 0000000000000000
> FS:  00007fd4381ff700(0000) GS:ffff88803ec00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000064 CR3: 0000000028c0f000 CR4: 00000000003526f0
> DR0: 0000000000000000 DR1: 0000000000000002 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  evict+0x122/0x230 fs/inode.c:664
>  iput_final fs/inode.c:1747 [inline]
>  iput fs/inode.c:1773 [inline]
>  iput+0x317/0x390 fs/inode.c:1759
>  init_journal fs/gfs2/ops_fstype.c:875 [inline]
>  init_inodes+0x433/0xd80 fs/gfs2/ops_fstype.c:889
>  gfs2_fill_super+0x9a2/0xf20 fs/gfs2/ops_fstype.c:1247
>  get_tree_bdev+0x224/0x320 fs/super.c:1324
>  gfs2_get_tree+0x27/0xd0 fs/gfs2/ops_fstype.c:1330
>  vfs_get_tree+0x2c/0x100 fs/super.c:1531
>  do_new_mount fs/namespace.c:3040 [inline]
>  path_mount+0x75c/0x1020 fs/namespace.c:3370
>  do_mount+0xa2/0xc0 fs/namespace.c:3383
>  __do_sys_mount fs/namespace.c:3591 [inline]
>  __se_sys_mount fs/namespace.c:3568 [inline]
>  __x64_sys_mount+0x13e/0x150 fs/namespace.c:3568
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x34/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x46174a
> Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 bd 86 fb ff c3 66
> 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d
> 01 f0 ff ff 0f 83 9a 86 fb ff c3 66 0f 1f 84 00 00 00 00 00
> RSP: 002b:00007fd4381fea78 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007fd4381feb10 RCX: 000000000046174a
> RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007fd4381fead0
> RBP: 00007fd4381fead0 R08: 00007fd4381feb10 R09: 0000000020000000
> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000020000000
> R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020047a20
>  </TASK>
> Modules linked in:
> CR2: 0000000000000064
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:evict_linked_inode fs/gfs2/super.c:1330 [inline]
> RIP: 0010:gfs2_evict_inode+0x449/0xb70 fs/gfs2/super.c:1385
> Code: 00 00 00 48 89 df e8 46 13 5a ff 48 8b bb a8 02 00 00 31 f6 e8
> d8 70 fd ff 48 8b 4c 24 20 31 f6 48 8b 81 b0 05 00 00 48 89 cf <8b> 50
> 64 e8 5f 4b 00 00 31 ff 41 89 c7 89 c6 e8 e3 86 2d ff 45 85
> RSP: 0018:ffff88802aec3a80 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: ffff88800eb70f00 RCX: ffff888028c58000
> RDX: ffffc900092dc000 RSI: 0000000000000000 RDI: ffff888028c58000
> RBP: ffff88802aec3b38 R08: ffffffff81fb50c2 R09: 0000000000000000
> R10: 0000000000000005 R11: 0000000000000000 R12: ffff88800eb71228
> R13: ffff88800eb71078 R14: ffff888028c58000 R15: 0000000000000000
> FS:  00007fd4381ff700(0000) GS:ffff88803ec00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000064 CR3: 0000000028c0f000 CR4: 00000000003526f0
> DR0: 0000000000000000 DR1: 0000000000000002 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
>    0: 00 00                 add    %al,(%rax)
>    2: 00 48 89             add    %cl,-0x77(%rax)
>    5: df e8                 fucomip %st(0),%st
>    7: 46 13 5a ff           rex.RX adc -0x1(%rdx),%r11d
>    b: 48 8b bb a8 02 00 00 mov    0x2a8(%rbx),%rdi
>   12: 31 f6                 xor    %esi,%esi
>   14: e8 d8 70 fd ff       callq  0xfffd70f1
>   19: 48 8b 4c 24 20       mov    0x20(%rsp),%rcx
>   1e: 31 f6                 xor    %esi,%esi
>   20: 48 8b 81 b0 05 00 00 mov    0x5b0(%rcx),%rax
>   27: 48 89 cf             mov    %rcx,%rdi
> * 2a: 8b 50 64             mov    0x64(%rax),%edx <-- trapping instruction
>   2d: e8 5f 4b 00 00       callq  0x4b91
>   32: 31 ff                 xor    %edi,%edi
>   34: 41 89 c7             mov    %eax,%r15d
>   37: 89 c6                 mov    %eax,%esi
>   39: e8 e3 86 2d ff       callq  0xff2d8721
>   3e: 45                   rex.RB
>   3f: 85                   .byte 0x85
>
> Best,
> Wei
>
> On Mon, 31 Oct 2022 at 21:25, Wei Chen <harperchen1110@xxxxxxxxx> wrote:
> >
> > Dear Linux developers,
> >
> > Here is the link to the reproducers.
> >
> > C reproducer: https://drive.google.com/file/d/1P9GsW2pvEN_tvn89RYsrgnv2uDz3_6iq/view?usp=share_link
> > Syz reproducer:
> > https://drive.google.com/file/d/1Be-QEZ-hfj_CXhXlSEvzbf3E89HmkVMH/view?usp=share_link
> >
> > The bug persists in the latest commit, v5.15.76 (4f5365f77018). I hope
> > it is helpful to you.
> >
> > [   83.919419][ T6891]   function = gfs2_dirent_scan, file =
> > fs/gfs2/dir.c, line = 602
> > [   83.923713][ T6891] gfs2: fsid=syz:syz.0: about to withdraw this file system
> > [   83.929444][ T6891] gfs2: fsid=syz:syz.0: File system withdrawn
> > [   83.931468][ T6891] CPU: 1 PID: 6891 Comm: a.out Not tainted 5.15.76 #5
> > [   83.933492][ T6891] Hardware name: QEMU Standard PC (i440FX + PIIX,
> > 1996), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
> > [   83.936328][ T6891] Call Trace:
> > [   83.937107][ T6891]  <TASK>
> > [   83.937780][ T6891]  dump_stack_lvl+0x8d/0xcf
> > [   83.938843][ T6891]  gfs2_withdraw+0x212/0x730
> > [   83.939908][ T6891]  ? gfs2_dirent_scan+0x158/0x1a0
> > [   83.941070][ T6891]  gfs2_dirent_scan+0x158/0x1a0
> > [   83.942185][ T6891]  ? do_filldir_main.isra.21+0x1e0/0x1e0
> > [   83.943476][ T6891]  ? do_filldir_main.isra.21+0x1e0/0x1e0
> > [   83.944765][ T6891]  gfs2_dirent_search+0x156/0x2b0
> > [   83.945928][ T6891]  gfs2_dir_search+0x4a/0x120
> > [   83.947005][ T6891]  gfs2_lookupi+0x1ec/0x2c0
> > [   83.948042][ T6891]  ? gfs2_lookupi+0x12d/0x2c0
> > [   83.949127][ T6891]  ? gfs2_lookup_simple+0x57/0x90
> > [   83.950403][ T6891]  gfs2_lookup_simple+0x57/0x90
> > [   83.951522][ T6891]  init_inodes+0x6c/0xfd0
> > [   83.952527][ T6891]  ? snprintf+0x66/0x90
> > [   83.953544][ T6891]  ? gfs2_fill_super+0xa4d/0x1080
> > [   83.954695][ T6891]  gfs2_fill_super+0xa4d/0x1080
> > [   83.955809][ T6891]  ? gfs2_glock_nq_num+0x8f/0xe0
> > [   83.956946][ T6891]  ? snprintf+0x66/0x90
> > [   83.957905][ T6891]  ? set_blocksize+0x100/0x130
> > [   83.959011][ T6891]  ? gfs2_reconfigure+0x4c0/0x4c0
> > [   83.960164][ T6891]  ? get_tree_bdev+0x1c9/0x310
> > [   83.961270][ T6891]  get_tree_bdev+0x1c9/0x310
> > [   83.962579][ T6891]  gfs2_get_tree+0x24/0xc0
> > [   83.963992][ T6891]  vfs_get_tree+0x28/0x100
> > [   83.965423][ T6891]  path_mount+0x926/0xce0
> > [   83.966878][ T6891]  ? putname+0x83/0xa0
> > [   83.968251][ T6891]  do_mount+0x92/0xb0
> > [   83.969599][ T6891]  __x64_sys_mount+0xb0/0x120
> > [   83.971115][ T6891]  do_syscall_64+0x34/0xb0
> > [   83.972527][ T6891]  entry_SYSCALL_64_after_hwframe+0x61/0xcb
> > [   83.974433][ T6891] RIP: 0033:0x7f4669d7f48a
> > [   83.975836][ T6891] Code: 48 8b 0d 11 fa 2a 00 f7 d8 64 89 01 48 83
> > c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5
> > 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d de f9 2a 00 f7 d8
> > 64 89 01 48
> > [   83.982060][ T6891] RSP: 002b:00007f466a46bd38 EFLAGS: 00000282
> > ORIG_RAX: 00000000000000a5
> > [   83.984695][ T6891] RAX: ffffffffffffffda RBX: 0000000000000000
> > RCX: 00007f4669d7f48a
> > [   83.986856][ T6891] RDX: 0000000020000000 RSI: 0000000020000100
> > RDI: 00007f466a46be70
> > [   83.988696][ T6891] RBP: 00007f466a46bef0 R08: 00007f466a46bd70
> > R09: 0000000000000000
> > [   83.990534][ T6891] R10: 0000000000000000 R11: 0000000000000282
> > R12: 00007ffd64dee9fe
> > [   83.992369][ T6891] R13: 00007ffd64dee9ff R14: 00007f466a44c000
> > R15: 0000000000000003
> > [   83.994218][ T6891]  </TASK>
> > [   83.997025][ T6891] gfs2: fsid=syz:syz.0: can't lookup journal index: 0
> > [   83.998884][ T6891] BUG: kernel NULL pointer dereference, address:
> > 000000000000008c
> > [   84.000696][ T6891] #PF: supervisor read access in kernel mode
> > [   84.002075][ T6891] #PF: error_code(0x0000) - not-present page
> > [   84.003452][ T6891] PGD 109056067 P4D 109056067 PUD 109057067 PMD 0
> > [   84.004955][ T6891] Oops: 0000 [#1] PREEMPT SMP
> > [   84.006026][ T6891] CPU: 1 PID: 6891 Comm: a.out Not tainted 5.15.76 #5
> > [   84.007585][ T6891] Hardware name: QEMU Standard PC (i440FX + PIIX,
> > 1996), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
> > [   84.010444][ T6891] RIP: 0010:gfs2_evict_inode+0x39f/0x910
> > [   84.011742][ T6891] Code: 02 37 ff be 01 00 00 00 48 89 df e8 ab 38
> > 60 ff 48 8b bb b8 04 00 00 31 f6 e8 7d 95 fd ff 49 8b 87 00 09 00 00
> > 31 f6 4c 89 ff <8b> 90 8c 00 00 00 e8 56 43 00 00 85 c0 89 85 60 ff ff
> > ff 75 25 e8
> > [   84.016251][ T6891] RSP: 0018:ffffc900025d3b00 EFLAGS: 00010246
> > [   84.017655][ T6891] RAX: 0000000000000000 RBX: ffff88810cb10650
> > RCX: 0000000000000000
> > [   84.019490][ T6891] RDX: ffff88810ab15340 RSI: 0000000000000000
> > RDI: ffff88810c1bc000
> > [   84.021329][ T6891] RBP: ffffc900025d3bb0 R08: 0000000000000001
> > R09: 0000000000000000
> > [   84.023160][ T6891] R10: ffffc900025d38f8 R11: 0000000000000001
> > R12: ffff88810cb10b88
> > [   84.024992][ T6891] R13: ffff88810cb10878 R14: ffff88810c1bc000
> > R15: ffff88810c1bc000
> > [   84.026825][ T6891] FS:  00007f466a46c700(0000)
> > GS:ffff88813dc00000(0000) knlGS:0000000000000000
> > [   84.028869][ T6891] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [   84.030382][ T6891] CR2: 000000000000008c CR3: 000000010c054000
> > CR4: 00000000003506e0
> > [   84.032206][ T6891] DR0: 0000000000000000 DR1: 0000000000000000
> > DR2: 0000000000000000
> > [   84.034034][ T6891] DR3: 0000000000000000 DR6: 00000000fffe0ff0
> > DR7: 0000000000000400
> > [   84.035859][ T6891] Call Trace:
> > [   84.036615][ T6891]  <TASK>
> > [   84.037294][ T6891]  ? find_held_lock+0x2d/0x90
> > [   84.038375][ T6891]  ? gfs2_evict_inode+0x2c7/0x910
> > [   84.039537][ T6891]  ? evict_unlinked_inode+0x380/0x380
> > [   84.040773][ T6891]  ? evict+0xfd/0x1e0
> > [   84.041694][ T6891]  evict+0xfd/0x1e0
> > [   84.042571][ T6891]  ? gfs2_glock_put_eventually+0x40/0x40
> > [   84.043866][ T6891]  iput.part.20+0x217/0x3a0
> > [   84.044949][ T6891]  iput+0x29/0x40
> > [   84.045790][ T6891]  dentry_unlink_inode+0x163/0x170
> > [   84.046971][ T6891]  __dentry_kill+0x137/0x220
> > [   84.048032][ T6891]  ? dput+0x32/0x650
> > [   84.048936][ T6891]  dput+0x42b/0x650
> > [   84.049814][ T6891]  gfs2_fill_super+0xa94/0x1080
> > [   84.050932][ T6891]  ? gfs2_glock_nq_num+0x8f/0xe0
> > [   84.052068][ T6891]  ? snprintf+0x66/0x90
> > [   84.053036][ T6891]  ? set_blocksize+0x100/0x130
> > [   84.054137][ T6891]  ? gfs2_reconfigure+0x4c0/0x4c0
> > [   84.055292][ T6891]  ? get_tree_bdev+0x1c9/0x310
> > [   84.056391][ T6891]  get_tree_bdev+0x1c9/0x310
> > [   84.057457][ T6891]  gfs2_get_tree+0x24/0xc0
> > [   84.058474][ T6891]  vfs_get_tree+0x28/0x100
> > [   84.059489][ T6891]  path_mount+0x926/0xce0
> > [   84.060486][ T6891]  ? putname+0x83/0xa0
> > [   84.061432][ T6891]  do_mount+0x92/0xb0
> > [   84.062353][ T6891]  __x64_sys_mount+0xb0/0x120
> > [   84.063437][ T6891]  do_syscall_64+0x34/0xb0
> > [   84.064455][ T6891]  entry_SYSCALL_64_after_hwframe+0x61/0xcb
> > [   84.065811][ T6891] RIP: 0033:0x7f4669d7f48a
> > [   84.066822][ T6891] Code: 48 8b 0d 11 fa 2a 00 f7 d8 64 89 01 48 83
> > c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5
> > 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d de f9 2a 00 f7 d8
> > 64 89 01 48
> > [   84.071310][ T6891] RSP: 002b:00007f466a46bd38 EFLAGS: 00000282
> > ORIG_RAX: 00000000000000a5
> > [   84.073242][ T6891] RAX: ffffffffffffffda RBX: 0000000000000000
> > RCX: 00007f4669d7f48a
> > [   84.075069][ T6891] RDX: 0000000020000000 RSI: 0000000020000100
> > RDI: 00007f466a46be70
> > [   84.076892][ T6891] RBP: 00007f466a46bef0 R08: 00007f466a46bd70
> > R09: 0000000000000000
> > [   84.078724][ T6891] R10: 0000000000000000 R11: 0000000000000282
> > R12: 00007ffd64dee9fe
> > [   84.080598][ T6891] R13: 00007ffd64dee9ff R14: 00007f466a44c000
> > R15: 0000000000000003
> > [   84.082437][ T6891]  </TASK>
> > [   84.083141][ T6891] Modules linked in:
> > [   84.084084][ T6891] CR2: 000000000000008c
> > [   84.085089][ T6891] ---[ end trace 7249ef596cc64205 ]---
> > [   84.086343][ T6891] RIP: 0010:gfs2_evict_inode+0x39f/0x910
> > [   84.087642][ T6891] Code: 02 37 ff be 01 00 00 00 48 89 df e8 ab 38
> > 60 ff 48 8b bb b8 04 00 00 31 f6 e8 7d 95 fd ff 49 8b 87 00 09 00 00
> > 31 f6 4c 89 ff <8b> 90 8c 00 00 00 e8 56 43 00 00 85 c0 89 85 60 ff ff
> > ff 75 25 e8
> > [   84.092183][ T6891] RSP: 0018:ffffc900025d3b00 EFLAGS: 00010246
> > [   84.093581][ T6891] RAX: 0000000000000000 RBX: ffff88810cb10650
> > RCX: 0000000000000000
> > [   84.095407][ T6891] RDX: ffff88810ab15340 RSI: 0000000000000000
> > RDI: ffff88810c1bc000
> > [   84.097245][ T6891] RBP: ffffc900025d3bb0 R08: 0000000000000001
> > R09: 0000000000000000
> > [   84.099079][ T6891] R10: ffffc900025d38f8 R11: 0000000000000001
> > R12: ffff88810cb10b88
> > [   84.100917][ T6891] R13: ffff88810cb10878 R14: ffff88810c1bc000
> > R15: ffff88810c1bc000
> > [   84.102756][ T6891] FS:  00007f466a46c700(0000)
> > GS:ffff88813dc00000(0000) knlGS:0000000000000000
> > [   84.104808][ T6891] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [   84.106320][ T6891] CR2: 000000000000008c CR3: 000000010c054000
> > CR4: 00000000003506e0
> > [   84.108160][ T6891] DR0: 0000000000000000 DR1: 0000000000000000
> > DR2: 0000000000000000
> > [   84.109992][ T6891] DR3: 0000000000000000 DR6: 00000000fffe0ff0
> > DR7: 0000000000000400
> > [   84.111822][ T6891] Kernel panic - not syncing: Fatal exception
> > [   84.113908][ T6891] Kernel Offset: disabled
> > [   84.114912][ T6891] Rebooting in 86400 seconds..
> >
> > Best,
> > Wei
>
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