linux-kernel - Re: [syzbot] [ext4?] kernel BUG in ext4_write_inline

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Message-ID: <698c6858.050a0220.340abe.000e.GAE@google.com>
Date: Wed, 11 Feb 2026 03:30:32 -0800
From: syzbot <syzbot+7de5fe447862fc37576f@...kaller.appspotmail.com>
To: adilger.kernel@...ger.ca, kartikey406@...il.com, 
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com, tytso@....edu
Subject: Re: [syzbot] [ext4?] kernel BUG in ext4_write_inline_data (4)

syzbot has found a reproducer for the following issue on:

HEAD commit:    dc855b77719f Merge tag 'irq-drivers-2026-02-09' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=179e0b3a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c48edf5effbe2b83
dashboard link: https://syzkaller.appspot.com/bug?extid=7de5fe447862fc37576f
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=137b6ae6580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=109fb402580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d7c9816606c2/disk-dc855b77.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cb6f0c59d3d1/vmlinux-dc855b77.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7abf33193f14/bzImage-dc855b77.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/cc23e4e0f61c/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=11aaccaa580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7de5fe447862fc37576f@...kaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at fs/ext4/inline.c:240!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 6183 Comm: syz.1.27 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:ext4_write_inline_data+0x43c/0x440 fs/ext4/inline.c:240
Code: c1 38 c1 0f 8c 19 ff ff ff 48 89 df 49 89 d7 e8 3a 5d ac ff 4c 89 fa e9 06 ff ff ff e8 7d 31 43 ff 90 0f 0b e8 75 31 43 ff 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f
RSP: 0018:ffffc900041bf3a8 EFLAGS: 00010293
RAX: ffffffff8281434b RBX: 0000000000003000 RCX: ffff88802ab8dac0
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000003000
RBP: ffff888072ee11a2 R08: ffff88805b996387 R09: 1ffff1100b732c70
R10: dffffc0000000000 R11: ffffed100b732c71 R12: 000000000000003c
R13: ffffc900041bf460 R14: 0000000000002000 R15: ffff888072ee0c38
FS:  00007f67e2ffe6c0(0000) GS:ffff8881256ca000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555753c59e8 CR3: 0000000079001000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 ext4_write_inline_data_end+0x34d/0xad0 fs/ext4/inline.c:817
 generic_perform_write+0x620/0x8f0 mm/filemap.c:4335
 ext4_buffered_write_iter+0xce/0x3a0 fs/ext4/file.c:300
 ext4_file_write_iter+0x298/0x1c10 fs/ext4/file.c:-1
 iter_file_splice_write+0x99b/0x1100 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x101/0x160 fs/splice.c:1161
 splice_direct_to_actor+0x53a/0xc70 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x195/0x290 fs/splice.c:1230
 do_sendfile+0x535/0x7d0 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1419
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f67e399bf79
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f67e2ffe028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f67e3c15fa0 RCX: 00007f67e399bf79
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000004
RBP: 00007f67e3a327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000e3aa6ea R11: 0000000000000246 R12: 0000000000000000
R13: 00007f67e3c16038 R14: 00007f67e3c15fa0 R15: 00007fff789394f8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_write_inline_data+0x43c/0x440 fs/ext4/inline.c:240
Code: c1 38 c1 0f 8c 19 ff ff ff 48 89 df 49 89 d7 e8 3a 5d ac ff 4c 89 fa e9 06 ff ff ff e8 7d 31 43 ff 90 0f 0b e8 75 31 43 ff 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f
RSP: 0018:ffffc900041bf3a8 EFLAGS: 00010293

RAX: ffffffff8281434b RBX: 0000000000003000 RCX: ffff88802ab8dac0
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000003000
RBP: ffff888072ee11a2 R08: ffff88805b996387 R09: 1ffff1100b732c70
R10: dffffc0000000000 R11: ffffed100b732c71 R12: 000000000000003c
R13: ffffc900041bf460 R14: 0000000000002000 R15: ffff888072ee0c38
FS:  00007f67e2ffe6c0(0000) GS:ffff8881256ca000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa159255000 CR3: 0000000079001000 CR4: 0000000000350ef0


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.