Re: [syzbot] Re: [syzbot] [fs?] general protection fault in pagemap_scan_hugetlb_entry

From: syzbot
Date: Wed Dec 06 2023 - 14:18:39 EST

For archival purposes, forwarding an incoming command email to
linux-kernel@xxxxxxxxxxxxxxx, syzkaller-bugs@xxxxxxxxxxxxxxxx.

***

Subject: Re: [syzbot] [fs?] general protection fault in pagemap_scan_hugetlb_entry
Author: sidhartha.kumar@xxxxxxxxxx

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-hotfixes-unstable
________________________________
From: syzbot <syzbot+6e2ccedb96d1174e6a5f@xxxxxxxxxxxxxxxxxxxxxxxxx>
Sent: Saturday, December 2, 2023 6:17 PM
To: akpm@xxxxxxxxxxxxxxxxxxxx <akpm@xxxxxxxxxxxxxxxxxxxx>; dan.carpenter@xxxxxxxxxx <dan.carpenter@xxxxxxxxxx>; linux-fsdevel@xxxxxxxxxxxxxxx <linux-fsdevel@xxxxxxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx <linux-kernel@xxxxxxxxxxxxxxx>; linux-mm@xxxxxxxxx <linux-mm@xxxxxxxxx>; llvm@xxxxxxxxxxxxxxx <llvm@xxxxxxxxxxxxxxx>; Mike Kravetz <mike.kravetz@xxxxxxxxxx>; muchun.song@xxxxxxxxx <muchun.song@xxxxxxxxx>; nathan@xxxxxxxxxx <nathan@xxxxxxxxxx>; ndesaulniers@xxxxxxxxxx <ndesaulniers@xxxxxxxxxx>; Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>; syzkaller-bugs@xxxxxxxxxxxxxxxx <syzkaller-bugs@xxxxxxxxxxxxxxxx>; trix@xxxxxxxxxx <trix@xxxxxxxxxx>
Subject: [syzbot] [fs?] general protection fault in pagemap_scan_hugetlb_entry

Hello,

syzbot found the following issue on:

HEAD commit: df60cee26a2e Merge tag '6.7-rc3-smb3-server-fixes' of git:..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=17ad46fce80000
kernel config: https://syzkaller.appspot.com/x/.config?x=bb39fe85d254f638
dashboard link: https://syzkaller.appspot.com/bug?extid=6e2ccedb96d1174e6a5f
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17befd62e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10d5a90ce80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c632017e0dc4/disk-df60cee2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f94c8fa25aeb/vmlinux-df60cee2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/af80f80c708b/bzImage-df60cee2.xz

The issue was bisected to:

commit a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3
Author: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Date: Tue Sep 26 19:20:17 2023 +0000

mm/filemap: remove hugetlb special casing in filemap.c

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17f61552e80000
final oops: https://syzkaller.appspot.com/x/report.txt?x=140e1552e80000
console output: https://syzkaller.appspot.com/x/log.txt?x=100e1552e80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6e2ccedb96d1174e6a5f@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: a08c7193e4f1 ("mm/filemap: remove hugetlb special casing in filemap.c")

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: 5072 Comm: syz-executor107 Not tainted 6.7.0-rc3-syzkaller-00014-gdf60cee26a2e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
RIP: 0010:pagemap_scan_backout_range fs/proc/task_mmu.c:1946 [inline]
RIP: 0010:pagemap_scan_hugetlb_entry+0x6ca/0x1130 fs/proc/task_mmu.c:2254
Code: 3c 02 00 0f 85 68 09 00 00 48 8b 83 80 00 00 00 48 8d 04 40 4d 8d 6c c5 00 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 51 09 00 00 4d 8b 75 00 48 8b 7c 24 08 4c 89 f6
RSP: 0018:ffffc90003a2fa50 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffffc90003a2fdb0 RCX: ffffffff82111e46
RDX: 0000000000000000 RSI: ffffffff82111e54 RDI: ffffc90003a2fe30
RBP: 1ffff92000745f52 R08: 0000000000000006 R09: 0000000020ffc000
R10: 00000000211f9000 R11: ffffffff915f5de8 R12: ffff8880299e0300
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000020ffc000
FS: 0000555555c7b380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005fdeb8 CR3: 00000000752b4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
walk_hugetlb_range mm/pagewalk.c:326 [inline]
__walk_page_range+0x36c/0x770 mm/pagewalk.c:393
walk_page_range+0x626/0xa80 mm/pagewalk.c:521
do_pagemap_scan+0x40d/0xcd0 fs/proc/task_mmu.c:2437
do_pagemap_cmd+0x5e/0x80 fs/proc/task_mmu.c:2478
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl fs/ioctl.c:857 [inline]
__x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f171819d669
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffbe81bb68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fffbe81bb80 RCX: 00007f171819d669
RDX: 0000000020000040 RSI: 00000000c0606610 RDI: 0000000000000003
RBP: 00007f1718210610 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000286 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fffbe81bdb8 R14: 0000000000000001 R15: 0000000000000001
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:pagemap_scan_backout_range fs/proc/task_mmu.c:1946 [inline]
RIP: 0010:pagemap_scan_hugetlb_entry+0x6ca/0x1130 fs/proc/task_mmu.c:2254
Code: 3c 02 00 0f 85 68 09 00 00 48 8b 83 80 00 00 00 48 8d 04 40 4d 8d 6c c5 00 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 51 09 00 00 4d 8b 75 00 48 8b 7c 24 08 4c 89 f6
RSP: 0018:ffffc90003a2fa50 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffffc90003a2fdb0 RCX: ffffffff82111e46
RDX: 0000000000000000 RSI: ffffffff82111e54 RDI: ffffc90003a2fe30
RBP: 1ffff92000745f52 R08: 0000000000000006 R09: 0000000020ffc000
R10: 00000000211f9000 R11: ffffffff915f5de8 R12: ffff8880299e0300
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000020ffc000
FS: 0000555555c7b380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005fdeb8 CR3: 00000000752b4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 3c 02 cmp $0x2,%al
2: 00 0f add %cl,(%rdi)
4: 85 68 09 test %ebp,0x9(%rax)
7: 00 00 add %al,(%rax)
9: 48 8b 83 80 00 00 00 mov 0x80(%rbx),%rax
10: 48 8d 04 40 lea (%rax,%rax,2),%rax
14: 4d 8d 6c c5 00 lea 0x0(%r13,%rax,8),%r13
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 4c 89 ea mov %r13,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 51 09 00 00 jne 0x985
34: 4d 8b 75 00 mov 0x0(%r13),%r14
38: 48 8b 7c 24 08 mov 0x8(%rsp),%rdi
3d: 4c 89 f6 mov %r14,%rsi


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

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.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup