[syzbot] [jfs?] divide error in dbAllocAG

[syzbot] [jfs?] divide error in dbAllocAG

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    7af08b57bcb9 Merge tag 'trace-v6.13-2' of git://git.kernel..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=15e03f5f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=29e5eaaea951b791
dashboard link: https://syzkaller.appspot.com/bug?extid=7c808908291a569281a9
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=162573c0580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=156dcd30580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/815d3cc889bc/disk-7af08b57.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fa365742e0ed/vmlinux-7af08b57.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ea9d8aace8b7/bzImage-7af08b57.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/83512543e1fa/mount_0.gz

The issue was bisected to:

commit 2b9ac22b12a266eb4fec246a07b504dd4983b16b
Author: Kristian Klausen <kristian@klausen.dk>
Date:   Fri Jun 18 11:51:57 2021 +0000

    loop: Fix missing discard support when using LOOP_CONFIGURE

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=17166d30580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=14966d30580000
console output: https://syzkaller.appspot.com/x/log.txt?x=10966d30580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com
Fixes: 2b9ac22b12a2 ("loop: Fix missing discard support when using LOOP_CONFIGURE")

loop0: detected capacity change from 0 to 32768
Oops: divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5857 Comm: syz-executor194 Not tainted 6.12.0-syzkaller-10689-g7af08b57bcb9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:dbAllocAG+0x414/0xd30 fs/jfs/jfs_dmap.c:1399
Code: 03 0f b6 0c 11 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 a7 08 00 00 41 8b 4d 2c 49 8d 7d 30 99 48 89 fe 48 c1 ee 03 <f7> f9 48 ba 00 00 00 00 00 fc ff df 0f b6 14 16 84 d2 74 09 80 fa
RSP: 0018:ffffc9000450fbc8 EFLAGS: 00010216
RAX: 0000000000000400 RBX: 000000000000000a RCX: 0000000000000000
RDX: 0000000000000000 RSI: 1ffff11004cce406 RDI: ffff888026672030
RBP: 0000000000000000 R08: 0000000000000005 R09: 000000000000001f
R10: 000000000000000a R11: 0000000000000002 R12: ffff88807650f000
R13: ffff888026672000 R14: 0000000000000000 R15: 000000000000000c
FS:  000055558401d380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557f78216048 CR3: 00000000772e0000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 dbDiscardAG+0x249/0x7c0 fs/jfs/jfs_dmap.c:1613
 jfs_ioc_trim+0x3fb/0x5c0 fs/jfs/jfs_discard.c:105
 jfs_ioctl+0x335/0x430 fs/jfs/ioctl.c:131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc4a885b679
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc0fc54e38 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffc0fc55008 RCX: 00007fc4a885b679
RDX: 0000000020000080 RSI: 00000000c0185879 RDI: 0000000000000004
RBP: 00007fc4a88d4610 R08: 0000000000000000 R09: 00007ffc0fc55008
R10: 0000000000005ea7 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc0fc54ff8 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbAllocAG+0x414/0xd30 fs/jfs/jfs_dmap.c:1399
Code: 03 0f b6 0c 11 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 a7 08 00 00 41 8b 4d 2c 49 8d 7d 30 99 48 89 fe 48 c1 ee 03 <f7> f9 48 ba 00 00 00 00 00 fc ff df 0f b6 14 16 84 d2 74 09 80 fa
RSP: 0018:ffffc9000450fbc8 EFLAGS: 00010216
RAX: 0000000000000400 RBX: 000000000000000a RCX: 0000000000000000
RDX: 0000000000000000 RSI: 1ffff11004cce406 RDI: ffff888026672030
RBP: 0000000000000000 R08: 0000000000000005 R09: 000000000000001f
R10: 000000000000000a R11: 0000000000000002 R12: ffff88807650f000
R13: ffff888026672000 R14: 0000000000000000 R15: 000000000000000c
FS:  000055558401d380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557f78216048 CR3: 00000000772e0000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess):
   0:	03 0f                	add    (%rdi),%ecx
   2:	b6 0c                	mov    $0xc,%dh
   4:	11 48 89             	adc    %ecx,-0x77(%rax)
   7:	fa                   	cli
   8:	83 e2 07             	and    $0x7,%edx
   b:	83 c2 03             	add    $0x3,%edx
   e:	38 ca                	cmp    %cl,%dl
  10:	7c 08                	jl     0x1a
  12:	84 c9                	test   %cl,%cl
  14:	0f 85 a7 08 00 00    	jne    0x8c1
  1a:	41 8b 4d 2c          	mov    0x2c(%r13),%ecx
  1e:	49 8d 7d 30          	lea    0x30(%r13),%rdi
  22:	99                   	cltd
  23:	48 89 fe             	mov    %rdi,%rsi
  26:	48 c1 ee 03          	shr    $0x3,%rsi
* 2a:	f7 f9                	idiv   %ecx <-- trapping instruction
  2c:	48 ba 00 00 00 00 00 	movabs $0xdffffc0000000000,%rdx
  33:	fc ff df
  36:	0f b6 14 16          	movzbl (%rsi,%rdx,1),%edx
  3a:	84 d2                	test   %dl,%dl
  3c:	74 09                	je     0x47
  3e:	80                   	.byte 0x80
  3f:	fa                   	cli


---
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Re: [syzbot] [jfs?] divide error in dbAllocAG

[Edward Adam Davis]

#syz test: https://github.com/ea1davis/linux jfs/syz

Re: [syzbot] [jfs?] divide error in dbAllocAG

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com
Tested-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com

Tested on:

commit:         62cc82b7 jfs: check agwidth and agheight before alloca..
git tree:       https://github.com/ea1davis/linux jfs/syz
console output: https://syzkaller.appspot.com/x/log.txt?x=11a7afc0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=18d90fa8ec96d8b0
dashboard link: https://syzkaller.appspot.com/bug?extid=7c808908291a569281a9
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [jfs?] divide error in dbAllocAG

[Edward Adam Davis]

#syz test: https://github.com/ea1davis/linux jfs/syzv2

Re: [syzbot] [jfs?] divide error in dbAllocAG

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com
Tested-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com

Tested on:

commit:         a4326560 jfs: check agwidth and agheight when dbmount
git tree:       https://github.com/ea1davis/linux jfs/syzv2
console output: https://syzkaller.appspot.com/x/log.txt?x=113740f8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=18d90fa8ec96d8b0
dashboard link: https://syzkaller.appspot.com/bug?extid=7c808908291a569281a9
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [jfs?] divide error in dbAllocAG

[Edward Adam Davis]

#syz test: https://github.com/ea1davis/linux jfs/syzv3

Re: [syzbot] [jfs?] divide error in dbAllocAG

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com
Tested-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com

Tested on:

commit:         842f896c jfs: check agwidth before calculating the con..
git tree:       https://github.com/ea1davis/linux jfs/syzv3
console output: https://syzkaller.appspot.com/x/log.txt?x=17ee75e8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=18d90fa8ec96d8b0
dashboard link: https://syzkaller.appspot.com/bug?extid=7c808908291a569281a9
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.

[PATCH] jfs: check agwidth before calculating the control page level

[Edward Adam Davis]

The width in dmapctl of the AG is zero, it trigger a divide error when
calculating the control page level in dbAllocAG.

To avoid this issue, add a check for agwidth in dbAllocAG.

Reported-and-tested-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7c808908291a569281a9
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 fs/jfs/jfs_dmap.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index f9009e4f9ffd..2377102d9c4c 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -1373,6 +1373,11 @@ dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb, s64 * results)
 		return (rc);
 	}
 
+	if (!bmp->db_agwidth) {
+		jfs_error(bmp->db_ipbmap->i_sb, "width in dmapctl of the AG is zero\n");
+		return -EIO;
+	}
+
 	/* the buffer for the dmap control page that fully describes the
 	 * allocation group.
 	 */
-- 
2.47.0

Re: [Jfs-discussion] [PATCH] jfs: check agwidth before calculating the control page level

[Dave Kleikamp]

Catching up on long-ignored emails.

On 12/3/24 4:22AM, Edward Adam Davis via Jfs-discussion wrote:
> The width in dmapctl of the AG is zero, it trigger a divide error when
> calculating the control page level in dbAllocAG.
> 
> To avoid this issue, add a check for agwidth in dbAllocAG.

This value shouldn't change unless the filesystem is resized. I would 
prefer that the check was made once in dbMount().

Shaggy

> 
> Reported-and-tested-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=7c808908291a569281a9
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
>   fs/jfs/jfs_dmap.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
> index f9009e4f9ffd..2377102d9c4c 100644
> --- a/fs/jfs/jfs_dmap.c
> +++ b/fs/jfs/jfs_dmap.c
> @@ -1373,6 +1373,11 @@ dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb, s64 * results)
>   		return (rc);
>   	}
>   
> +	if (!bmp->db_agwidth) {
> +		jfs_error(bmp->db_ipbmap->i_sb, "width in dmapctl of the AG is zero\n");
> +		return -EIO;
> +	}
> +
>   	/* the buffer for the dmap control page that fully describes the
>   	 * allocation group.
>   	 */

[PATCH V2] jfs: add sanity check for agwidth in dbMount

[Edward Adam Davis]

The width in dmapctl of the AG is zero, it trigger a divide error when
calculating the control page level in dbAllocAG.

To avoid this issue, add a check for agwidth in dbAllocAG.

Reported-and-tested-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7c808908291a569281a9
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
V1 -> V2: move the check to dbMount

 fs/jfs/jfs_dmap.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index f9009e4f9ffd..62f55e7ed840 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -204,6 +204,10 @@ int dbMount(struct inode *ipbmap)
 	bmp->db_aglevel = le32_to_cpu(dbmp_le->dn_aglevel);
 	bmp->db_agheight = le32_to_cpu(dbmp_le->dn_agheight);
 	bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth);
+	if (!bmp->db_agwidth) {
+		err = -EINVAL;
+		goto err_release_metapage;
+	}
 	bmp->db_agstart = le32_to_cpu(dbmp_le->dn_agstart);
 	bmp->db_agl2size = le32_to_cpu(dbmp_le->dn_agl2size);
 	if (bmp->db_agl2size > L2MAXL2SIZE - L2MAXAG ||
-- 
2.43.0

Re: [PATCH V2] jfs: add sanity check for agwidth in dbMount

[Dave Kleikamp]

On 2/20/25 5:24AM, Edward Adam Davis wrote:
> The width in dmapctl of the AG is zero, it trigger a divide error when
> calculating the control page level in dbAllocAG.
> 
> To avoid this issue, add a check for agwidth in dbAllocAG.

Looks good. Will add this to jfs-next.

Thanks,
Shaggy

> 
> Reported-and-tested-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=7c808908291a569281a9
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
> V1 -> V2: move the check to dbMount
> 
>   fs/jfs/jfs_dmap.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
> index f9009e4f9ffd..62f55e7ed840 100644
> --- a/fs/jfs/jfs_dmap.c
> +++ b/fs/jfs/jfs_dmap.c
> @@ -204,6 +204,10 @@ int dbMount(struct inode *ipbmap)
>   	bmp->db_aglevel = le32_to_cpu(dbmp_le->dn_aglevel);
>   	bmp->db_agheight = le32_to_cpu(dbmp_le->dn_agheight);
>   	bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth);
> +	if (!bmp->db_agwidth) {
> +		err = -EINVAL;
> +		goto err_release_metapage;
> +	}
>   	bmp->db_agstart = le32_to_cpu(dbmp_le->dn_agstart);
>   	bmp->db_agl2size = le32_to_cpu(dbmp_le->dn_agl2size);
>   	if (bmp->db_agl2size > L2MAXL2SIZE - L2MAXAG ||