syzbot


WARNING in ext2_get_group_desc

Status: upstream: reported C repro on 2026/02/03 02:28
Reported-by: syzbot+aef8993536330b542f30@syzkaller.appspotmail.com
First crash: 42d, last: 42d
Fix bisection: failed (error log, bisect log)
  
Bug presence (1)
Date Name Commit Repro Result
2026/03/17 upstream (ToT) 2d1373e4246d C Failed due to an error; will retry later
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in ext2_get_group_desc ext4 -1 1 1339d 1335d 22/29 fixed on 2023/02/24 13:50

Sample crash report:
loop0: detected capacity change from 0 to 512
------------[ cut here ]------------
block_group >= groups_count - block_group = 51055371, groups_count = 1
WARNING: CPU: 0 PID: 4501 at fs/ext2/balloc.c:51 ext2_get_group_desc+0x184/0x210 fs/ext2/balloc.c:-1
Modules linked in:
CPU: 0 PID: 4501 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 : ffff800020ac77c0
x29: ffff800020ac77c0 x28: dfff800000000000 x27: 0000000061616160
x26: 1fffe0001a5220cf x25: dfff800000000000 x24: ffff0000e0ce6000
x23: 0000000000000001 x22: ffff0000d2910678 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 : 63bbd79d39899300
x8 : 63bbd79d39899300 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800020ac7258 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: 7846
hardirqs last  enabled at (7845): [<ffff80000830fb6c>] __up_console_sem+0xb4/0xfc kernel/printk/printk.c:261
hardirqs last disabled at (7846): [<ffff800011a1c234>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last  enabled at (7810): [<ffff800008030954>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (7808): [<ffff800008030920>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/03 06:06 linux-6.1.y cd9b81672742 d78927dd .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] [mounted in repro #3 (corrupt fs)] ci2-linux-6-1-kasan-arm64 WARNING in ext2_get_group_desc
2026/02/03 05:34 linux-6.1.y cd9b81672742 d78927dd .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] [mounted in repro #3 (corrupt fs)] ci2-linux-6-1-kasan-arm64 WARNING in ext2_get_group_desc
2026/02/03 05:01 linux-6.1.y cd9b81672742 d78927dd .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] [mounted in repro #3 (corrupt fs)] ci2-linux-6-1-kasan-arm64 WARNING in ext2_get_group_desc
2026/02/03 02:28 linux-6.1.y cd9b81672742 d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in ext2_get_group_desc
2026/02/03 02:28 linux-6.1.y cd9b81672742 d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in ext2_get_group_desc
* Struck through repros no longer work on HEAD.