Message-ID: <000000000000f3aeec05f025c6b8@google.com>
Date:   Sun, 18 Dec 2022 19:18:45 -0800
From:   syzbot <syzbot+9d014e6e0df70d97c103@...kaller.appspotmail.com>
To:     akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] BUG: unable to handle kernel NULL pointer dereference in
 unlock_page (2)

Hello,

syzbot found the following issue on:

HEAD commit:    a5541c0811a0 Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=10d2ebe0480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cbd4e584773e9397
dashboard link: https://syzkaller.appspot.com/bug?extid=9d014e6e0df70d97c103
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=107f999d880000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=170205af880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4b7702208fb9/disk-a5541c08.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9ec0153ec051/vmlinux-a5541c08.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6f8725ad290a/Image-a5541c08.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/327f2cb22964/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9d014e6e0df70d97c103@...kaller.appspotmail.com

 ksys_pread64 fs/read_write.c:665 [inline]
 __do_sys_pread64 fs/read_write.c:675 [inline]
 __se_sys_pread64 fs/read_write.c:672 [inline]
 __arm64_sys_pread64+0xbc/0x11c fs/read_write.c:672
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=000000010adf6000
[0000000000000008] pgd=0800000106a37003, p4d=0800000106a37003, pud=0800000106a36003, pmd=0000000000000000
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 3072 Comm: syz-executor288 Not tainted 6.1.0-rc8-syzkaller-33330-ga5541c0811a0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : _compound_head include/linux/page-flags.h:253 [inline]
pc : unlock_page+0x18/0xb8 mm/folio-compat.c:20
lr : unlock_page+0x18/0xb8 mm/folio-compat.c:19
sp : ffff80000ff1b910
x29: ffff80000ff1b910 x28: 0000000000000007 x27: fffffc000330a480
x26: 00000000ffffffff x25: 0000000000000000 x24: 0000000000000000
x23: 0000000000000001 x22: 0000000000000000 x21: 00000000fffffff4
x20: ffff0000c95b4880 x19: 0000000000000000 x18: 0000000000000073
x17: 6e69676e45206574 x16: ffff80000dbe6158 x15: ffff0000c4423480
x14: 0000000000000000 x13: 00000000ffffffff x12: ffff0000c4423480
x11: ff808000083f6804 x10: 0000000000000000 x9 : ffff8000083f6804
x8 : ffff0000c4423480 x7 : ffff80000c091ebc x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 unlock_page+0x18/0xb8 mm/folio-compat.c:19
 ni_readpage_cmpr+0x328/0x7cc fs/ntfs3/frecord.c:2139
 ntfs_read_folio+0xd8/0x128 fs/ntfs3/inode.c:697
 filemap_read_folio+0xc4/0x468 mm/filemap.c:2407
 filemap_create_folio+0xc0/0x1b4 mm/filemap.c:2536
 filemap_get_pages+0x388/0x598 mm/filemap.c:2588
 filemap_read+0x14c/0x6f4 mm/filemap.c:2675
 generic_file_read_iter+0x6c/0x25c mm/filemap.c:2821
 ntfs_file_read_iter+0xe4/0x118 fs/ntfs3/file.c:853
 call_read_iter include/linux/fs.h:2193 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x2d4/0x448 fs/read_write.c:470
 ksys_pread64 fs/read_write.c:665 [inline]
 __do_sys_pread64 fs/read_write.c:675 [inline]
 __se_sys_pread64 fs/read_write.c:672 [inline]
 __arm64_sys_pread64+0xbc/0x11c fs/read_write.c:672
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
Code: a9014ff4 910003fd aa0003f3 97fac089 (f9400674) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	a9014ff4 	stp	x20, x19, [sp, #16]
   4:	910003fd 	mov	x29, sp
   8:	aa0003f3 	mov	x19, x0
   c:	97fac089 	bl	0xffffffffffeb0230
* 10:	f9400674 	ldr	x20, [x19, #8] <-- trapping instruction


---
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