Re: [syzbot] [nilfs?] general protection fault in nilfs_clear_dirty_page

From: syzbot
Date: Sat Jun 10 2023 - 23:56:12 EST

syzbot has found a reproducer for the following issue on:

HEAD commit: 022ce8862dff Merge tag 'i2c-for-6.4-rc6' of git://git.kern..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=118151dd280000
kernel config: https://syzkaller.appspot.com/x/.config?x=7474de833c217bf4
dashboard link: https://syzkaller.appspot.com/bug?extid=53369d11851d8f26735c
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13e9d48b280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12d7fa63280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cb6ca005422c/disk-022ce886.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/172bf908a89e/vmlinux-022ce886.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4a00b7ed8430/bzImage-022ce886.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/edff56b4a75d/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+53369d11851d8f26735c@xxxxxxxxxxxxxxxxxxxxxxxxx

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 5040 Comm: syz-executor116 Not tainted 6.4.0-rc5-syzkaller-00305-g022ce8862dff #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
RIP: 0010:nilfs_clear_dirty_page+0xa9/0x1130 fs/nilfs2/page.c:388
Code: 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 1b 38 97 fe 48 8b 1b 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 f9 37 97 fe 4c 8b 2b 49 8d 5d 28 48
RSP: 0018:ffffc90003d2f2e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0001cb1900
RBP: ffffc90003d2f3b0 R08: ffffffff834bef29 R09: fffff94000396321
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffea0001cb1900
R13: 0000000000000000 R14: dffffc0000000000 R15: dffffc0000000000
FS: 00007f996874e700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055fe30356e00 CR3: 000000002995d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
nilfs_clear_dirty_pages+0x1e0/0x370 fs/nilfs2/page.c:373
nilfs_writepages+0x11c/0x160 fs/nilfs2/inode.c:165
do_writepages+0x3a6/0x670 mm/page-writeback.c:2551
filemap_fdatawrite_wbc+0x125/0x180 mm/filemap.c:390
__filemap_fdatawrite_range mm/filemap.c:423 [inline]
filemap_write_and_wait_range+0x1d4/0x2c0 mm/filemap.c:678
generic_file_read_iter+0x19e/0x540 mm/filemap.c:2805
call_read_iter include/linux/fs.h:1862 [inline]
generic_file_splice_read+0x240/0x640 fs/splice.c:419
do_splice_to fs/splice.c:902 [inline]
splice_direct_to_actor+0x40c/0xbd0 fs/splice.c:973
do_splice_direct+0x283/0x3d0 fs/splice.c:1082
do_sendfile+0x620/0xff0 fs/read_write.c:1254
__do_sys_sendfile64 fs/read_write.c:1322 [inline]
__se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1308
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f9970ac36f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 71 15 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:00007f996874e2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f9970b497b0 RCX: 00007f9970ac36f9
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000007
RBP: 00007f9970b15b1c R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000201005 R11: 0000000000000246 R12: 00007f9970b150c0
R13: 00000000200026c0 R14: 0032656c69662f2e R15: 00007f9970b497b8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:nilfs_clear_dirty_page+0xa9/0x1130 fs/nilfs2/page.c:388
Code: 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 1b 38 97 fe 48 8b 1b 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 f9 37 97 fe 4c 8b 2b 49 8d 5d 28 48
RSP: 0018:ffffc90003d2f2e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0001cb1900
RBP: ffffc90003d2f3b0 R08: ffffffff834bef29 R09: fffff94000396321
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffea0001cb1900
R13: 0000000000000000 R14: dffffc0000000000 R15: dffffc0000000000
FS: 00007f996874e700(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9970b1500a CR3: 000000002995d000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 48 89 d8 mov %rbx,%rax
3: 48 c1 e8 03 shr $0x3,%rax
7: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1)
c: 74 08 je 0x16
e: 48 89 df mov %rbx,%rdi
11: e8 1b 38 97 fe callq 0xfe973831
16: 48 8b 1b mov (%rbx),%rbx
19: 48 89 d8 mov %rbx,%rax
1c: 48 c1 e8 03 shr $0x3,%rax
20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
27: fc ff df
* 2a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 48 89 df mov %rbx,%rdi
33: e8 f9 37 97 fe callq 0xfe973831
38: 4c 8b 2b mov (%rbx),%r13
3b: 49 8d 5d 28 lea 0x28(%r13),%rbx
3f: 48 rex.W


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