[v6.1] WARNING in ext2_get_group_desc

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cd9b81672742 Linux 6.1.161
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14bfb322580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1adc0bfde2d8a4a
dashboard link: https://syzkaller.appspot.com/bug?extid=aef8993536330b542f30
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d21df4411014/disk-cd9b8167.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/246aed0358fb/vmlinux-cd9b8167.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a6f546504ec2/Image-cd9b8167.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aef899...@syzkaller.appspotmail.com

------------[ cut here ]------------
block_group >= groups_count - block_group = 51055371, groups_count = 1
WARNING: CPU: 0 PID: 4460 at fs/ext2/balloc.c:51 ext2_get_group_desc+0x184/0x210 fs/ext2/balloc.c:-1
Modules linked in:
CPU: 0 PID: 4460 Comm: syz.4.5 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : ext2_get_group_desc+0x184/0x210 fs/ext2/balloc.c:-1
lr : ext2_get_group_desc+0x180/0x210 fs/ext2/balloc.c:49
sp : ffff8000210d77c0
x29: ffff8000210d77c0 x28: dfff800000000000 x27: 0000000061616160
x26: 1fffe0001a116ccf x25: dfff800000000000 x24: ffff0000cfa3b800
x23: 0000000000000001 x22: ffff0000d08b6678 x21: 00000000030b0b0b
x20: 00000000030b0b0b x19: 0000000000000000 x18: 0000000000000000
x17: 0000000000000000 x16: ffff8000082d9364 x15: 0000000000000002
x14: 0000000000000001 x13: 1fffe00033eaaba3 x12: 0000000000080000
x11: 00000000000018d9 x10: ffff80002ce59000 x9 : 8faa0b6d3d726300
x8 : 8faa0b6d3d726300 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000210d7258 x4 : ffff8000152e4cc0 x3 : ffff800008538160
x2 : 0000000000000001 x1 : 0000000100000000 x0 : 0000000000000000
Call trace:
ext2_get_group_desc+0x184/0x210 fs/ext2/balloc.c:-1
ext2_get_inode+0x174/0x3c0 fs/ext2/inode.c:1317
ext2_iget+0xd8/0x17e0 fs/ext2/inode.c:1395
ext2_nfs_get_inode+0x110/0x1b8 fs/ext2/super.c:374
generic_fh_to_dentry+0x9c/0x104 fs/libfs.c:1072
ext2_fh_to_dentry+0x44/0x58 fs/ext2/super.c:388
exportfs_decode_fh_raw+0x14c/0x56c fs/exportfs/expfs.c:435
exportfs_decode_fh+0x50/0x80 fs/exportfs/expfs.c:575
do_handle_to_path fs/fhandle.c:152 [inline]
handle_to_path fs/fhandle.c:207 [inline]
do_handle_open+0x4dc/0x8d0 fs/fhandle.c:223
__do_sys_open_by_handle_at fs/fhandle.c:265 [inline]
__se_sys_open_by_handle_at fs/fhandle.c:256 [inline]
__arm64_sys_open_by_handle_at+0x80/0x94 fs/fhandle.c:256
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
irq event stamp: 7754
hardirqs last enabled at (7753): [<ffff80000830fb6c>] __up_console_sem+0xb4/0xfc kernel/printk/printk.c:261
hardirqs last disabled at (7754): [<ffff800011a1c234>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last enabled at (7714): [<ffff800008030954>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (7712): [<ffff800008030920>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: cd9b81672742 Linux 6.1.161
git tree: linux-6.1.y

console output: https://syzkaller.appspot.com/x/log.txt?x=14c95252580000

kernel config: https://syzkaller.appspot.com/x/.config?x=b1adc0bfde2d8a4a
dashboard link: https://syzkaller.appspot.com/bug?extid=aef8993536330b542f30
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12e7425a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=176bfc5a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d21df4411014/disk-cd9b8167.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/246aed0358fb/vmlinux-cd9b8167.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a6f546504ec2/Image-cd9b8167.gz.xz

mounted in repro #1: https://storage.googleapis.com/syzbot-assets/aef4e2f0520d/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=14e7425a580000)
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/e360310165dc/mount_5.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=11ad4402580000)
mounted in repro #3: https://storage.googleapis.com/syzbot-assets/696d8ceb4333/mount_6.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=17e47322580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aef899...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 512

------------[ cut here ]------------
block_group >= groups_count - block_group = 51055371, groups_count = 1

WARNING: CPU: 0 PID: 4559 at fs/ext2/balloc.c:51 ext2_get_group_desc+0x184/0x210 fs/ext2/balloc.c:-1
Modules linked in:
CPU: 0 PID: 4559 Comm: syz.0.17 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : ext2_get_group_desc+0x184/0x210 fs/ext2/balloc.c:-1
lr : ext2_get_group_desc+0x180/0x210 fs/ext2/balloc.c:49

sp : ffff8000210277c0
x29: ffff8000210277c0 x28: dfff800000000000 x27: 0000000061616160
x26: 1fffe0001a045ccf x25: dfff800000000000 x24: ffff0000d634b800
x23: 0000000000000001 x22: ffff0000d022e678 x21: 00000000030b0b0b

x20: 00000000030b0b0b x19: 0000000000000000 x18: 0000000000000000

x17: 0000000000000000 x16: ffff8000082d9364 x15: 0000000000000000
x14: 0000000000000001 x13: 1fffe00033eaaba3 x12: 0000000000ff0100
x11: ff00800008194238 x10: 0000000000000000 x9 : fe0faf0edbb48c00
x8 : fe0faf0edbb48c00 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800021027258 x4 : ffff8000152e4cc0 x3 : ffff800008538160

x2 : 0000000000000001 x1 : 0000000100000000 x0 : 0000000000000000
Call trace:
ext2_get_group_desc+0x184/0x210 fs/ext2/balloc.c:-1
ext2_get_inode+0x174/0x3c0 fs/ext2/inode.c:1317
ext2_iget+0xd8/0x17e0 fs/ext2/inode.c:1395
ext2_nfs_get_inode+0x110/0x1b8 fs/ext2/super.c:374
generic_fh_to_dentry+0x9c/0x104 fs/libfs.c:1072
ext2_fh_to_dentry+0x44/0x58 fs/ext2/super.c:388
exportfs_decode_fh_raw+0x14c/0x56c fs/exportfs/expfs.c:435
exportfs_decode_fh+0x50/0x80 fs/exportfs/expfs.c:575
do_handle_to_path fs/fhandle.c:152 [inline]
handle_to_path fs/fhandle.c:207 [inline]
do_handle_open+0x4dc/0x8d0 fs/fhandle.c:223
__do_sys_open_by_handle_at fs/fhandle.c:265 [inline]
__se_sys_open_by_handle_at fs/fhandle.c:256 [inline]
__arm64_sys_open_by_handle_at+0x80/0x94 fs/fhandle.c:256
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

irq event stamp: 8032
hardirqs last enabled at (8031): [<ffff80000830fb6c>] __up_console_sem+0xb4/0xfc kernel/printk/printk.c:261
hardirqs last disabled at (8032): [<ffff800011a1c234>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last enabled at (7996): [<ffff800008030954>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (7994): [<ffff800008030920>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19

---[ end trace 0000000000000000 ]---


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