kernel BUG at fs/ext4/inline.c:LINE!

kernel BUG at fs/ext4/inline.c:LINE!
Status: upstream: reported syz repro on 2020/10/14 12:01
Reported-by: syzbot+4faa160fa96bfba639f8@syzkaller.appspotmail.com
First crash: 13d, last: 13d

Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: kernel BUG at fs/ext4/inline.c:LINE! (log)
Repro: syz .config

Sample crash report:

------------[ cut here ]------------
kernel BUG at fs/ext4/inline.c:751!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 23920 Comm: syz-executor.3 Not tainted 5.9.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ext4_write_inline_data_end+0x847/0x880 fs/ext4/ext4.h:3341
Code: 38 c1 0f 8c 06 fc ff ff 4c 89 e7 e8 d3 ac b2 ff e9 f9 fb ff ff 48 ff cd 48 89 eb e9 69 fe ff ff e8 4e a5 49 06 e8 e9 c7 72 ff <0f> 0b e8 e2 c7 72 ff 0f 0b e8 db c7 72 ff 0f 0b e8 d4 c7 72 ff 0f
RSP: 0018:ffffc90005077940 EFLAGS: 00010293
RAX: ffffffff82023607 RBX: 0000000c00000000 RCX: ffff8880a6718140
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff82022f07 R09: ffffed100ead147b
R10: ffffed100ead147b R11: 0000000000000000 R12: 0000000000000000
R13: ffff88807568a5b8 R14: 0000000000000001 R15: dffffc0000000000
FS:  00007faa624ff700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6db9e8bdb8 CR3: 000000009d643000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ext4_write_end+0x225/0xef0 fs/ext4/inode.c:1274
 generic_perform_write+0x344/0x4e0 mm/filemap.c:3516
 ext4_buffered_write_iter+0x44d/0x5d0 fs/ext4/file.c:269
 ext4_file_write_iter+0x891/0x19b0 include/linux/fs.h:784
 do_iter_readv_writev+0x4f9/0x6c0 include/linux/fs.h:1876
 do_iter_write+0x164/0x610 fs/read_write.c:1026
 vfs_writev fs/read_write.c:1099 [inline]
 do_pwritev+0x234/0x430 fs/read_write.c:1196
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45de59
Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007faa624fec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000128
RAX: ffffffffffffffda RBX: 0000000000026400 RCX: 000000000045de59
RDX: 0000000000000001 RSI: 00000000200014c0 RDI: 0000000000000006
RBP: 000000000118c018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bfd4
R13: 00007ffc849922ef R14: 00007faa624ff9c0 R15: 000000000118bfd4
Modules linked in:
---[ end trace 636f601b36ee58e9 ]---
RIP: 0010:ext4_write_inline_data_end+0x847/0x880 fs/ext4/ext4.h:3341
Code: 38 c1 0f 8c 06 fc ff ff 4c 89 e7 e8 d3 ac b2 ff e9 f9 fb ff ff 48 ff cd 48 89 eb e9 69 fe ff ff e8 4e a5 49 06 e8 e9 c7 72 ff <0f> 0b e8 e2 c7 72 ff 0f 0b e8 db c7 72 ff 0f 0b e8 d4 c7 72 ff 0f
RSP: 0018:ffffc90005077940 EFLAGS: 00010293
RAX: ffffffff82023607 RBX: 0000000c00000000 RCX: ffff8880a6718140
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff82022f07 R09: ffffed100ead147b
R10: ffffed100ead147b R11: 0000000000000000 R12: 0000000000000000
R13: ffff88807568a5b8 R14: 0000000000000001 R15: dffffc0000000000
FS:  00007faa624ff700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000118c000 CR3: 000000009d643000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci-upstream-kasan-gce-smack-root	2020/10/10 21:03	upstream	6f2f486d	4a77ae0b	.config	log	report	syz			adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu