[syzbot] BUG: unable to handle kernel NULL pointer dereference in lock_page

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bbed346d5a96 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=100804a6880000
kernel config: https://syzkaller.appspot.com/x/.config?x=3a4a45d2d827c1e
dashboard link: https://syzkaller.appspot.com/bug?extid=77e4f005cb899d4268d1
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=111fa5f2880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13687212880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e8e91bc79312/disk-bbed346d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c1cb3fb3b77e/vmlinux-bbed346d.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/c8d7f5e1917f/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+77e4f0...@syzkaller.appspotmail.com

NILFS (loop0): segctord starting. Construction interval = 5 seconds, CP frequency < 30 seconds
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000168
Mem abort info:
ESR = 0x0000000096000004
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
Data abort info:
ISV = 0, ISS = 0x00000004
CM = 0, WnR = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000108bcf000
[0000000000000168] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 3032 Comm: segctord Not tainted 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : _compound_head include/linux/page-flags.h:253 [inline]
pc : lock_page+0x28/0x1e0 include/linux/pagemap.h:958
lr : lock_page+0x28/0x1e0 include/linux/pagemap.h:956
sp : ffff80001290bc00
x29: ffff80001290bc00 x28: ffff80001290bde0 x27: 000000000000001b
x26: fffffc000330d7c0 x25: ffff0000caa56d68 x24: ffff0000ca9fb1c0
x23: 0000000000000080 x22: ffff0000ca9fb130 x21: 0000000000000160
x20: ffff0000c91e10b8 x19: 0000000000000160 x18: 00000000000000c0
x17: ffff80000dd0b198 x16: ffff80000db49158 x15: ffff0000c3e63500
x14: 0000000000000000 x13: 00000000ffffffff x12: ffff0000c3e63500
x11: ff808000095d1a0c x10: 0000000000000000 x9 : 0000000000000000
x8 : 0000000000000000 x7 : ffff80000856806c x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000000 x3 : 0000000000000000
x2 : 0000000000000000 x1 : ffff80000cb431b1 x0 : 0000000000000000
Call trace:
lock_page+0x28/0x1e0 include/linux/pagemap.h:956
nilfs_segctor_prepare_write+0x6c/0x21c fs/nilfs2/segment.c:1658
nilfs_segctor_do_construct+0x9f4/0xee8 fs/nilfs2/segment.c:2068
nilfs_segctor_construct+0xa0/0x380 fs/nilfs2/segment.c:2375
nilfs_segctor_thread_construct fs/nilfs2/segment.c:2483 [inline]
nilfs_segctor_thread+0x180/0x660 fs/nilfs2/segment.c:2566
kthread+0x12c/0x158 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
Code: 9001df80 912a5000 52807781 97c7bd0e (f9400674)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 9001df80 adrp x0, 0x3bf0000
4: 912a5000 add x0, x0, #0xa94
8: 52807781 mov w1, #0x3bc // #956
c: 97c7bd0e bl 0xffffffffff1ef444
* 10: f9400674 ldr x20, [x19, #8] <-- trapping instruction


---
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[syzbot]

>
>
> 在2022年10月29日星期六 UTC+8 04:42:46<syzbot> 写道：
>
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit: bbed346d5a96 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=100804a6880000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=3a4a45d2d827c1e
>> dashboard link:
>> https://syzkaller.appspot.com/bug?extid=77e4f005cb899d4268d1
>> 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=111fa5f2880000
>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13687212880000
>>

>> nilfs_segment_usage_set_dirty() in nilfs_sufile_mark_dirty()
>
> #syz test https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git

I see the command but can't find the corresponding bug.
Please resend the email to syzbo...@syzkaller.appspotmail.com address
that is the sender of the bug report (also present in the Reported-by tag).

> bbed346d5a96
>
> --- a/fs/nilfs2/sufile.c
> +++ b/fs/nilfs2/sufile.c
> @@ -495,12 +495,18 @@ void nilfs_sufile_do_free(struct inode *sufile, __u64
> segnum,
> int nilfs_sufile_mark_dirty(struct inode *sufile, __u64 segnum)
> {
> struct buffer_head *bh;
> + void *kaddr;
> + struct nilfs_segment_usage *su;
> int ret;
>
> ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0, &bh);
> if (!ret) {
> mark_buffer_dirty(bh);
> nilfs_mdt_mark_dirty(sufile);
> + kaddr = kmap_atomic(bh->b_page);
> + su = nilfs_sufile_block_get_segment_usage(sufile, segnum,
> bh, kaddr);
> + nilfs_segment_usage_set_dirty(su);
> + kunmap_atomic(kaddr);
> brelse(bh);
> }
> return ret;
> --
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bug...@googlegroups.com.
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[陈中津]

在2022年10月29日星期六 UTC+8 04:42:46<syzbot> 写道：

Hello,

syzbot found the following issue on:

HEAD commit: bbed346d5a96 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=100804a6880000
kernel config: https://syzkaller.appspot.com/x/.config?x=3a4a45d2d827c1e
dashboard link: https://syzkaller.appspot.com/bug?extid=77e4f005cb899d4268d1
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=111fa5f2880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13687212880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e8e91bc79312/disk-bbed346d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c1cb3fb3b77e/vmlinux-bbed346d.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/c8d7f5e1917f/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+77e4f0...@syzkaller.appspotmail.com

 

nilfs_segment_usage_set_dirty() in nilfs_sufile_mark_dirty() 

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git bbed346d5a96

[syzbot]

I see the command but can't find the corresponding bug.
Please resend the email to syzbo...@syzkaller.appspotmail.com address
that is the sender of the bug report (also present in the Reported-by tag).

> bbed346d5a96
>
> --- a/fs/nilfs2/sufile.c
> +++ b/fs/nilfs2/sufile.c
> @@ -495,12 +495,18 @@ void nilfs_sufile_do_free(struct inode *sufile, __u64
> segnum,
> int nilfs_sufile_mark_dirty(struct inode *sufile, __u64 segnum)
> {
> struct buffer_head *bh;
> + void *kaddr;
> + struct nilfs_segment_usage *su;
> int ret;
>
> ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0, &bh);
> if (!ret) {
> mark_buffer_dirty(bh);
> nilfs_mdt_mark_dirty(sufile);
> + kaddr = kmap_atomic(bh->b_page);
> + su = nilfs_sufile_block_get_segment_usage(sufile, segnum,
> bh, kaddr);
> + nilfs_segment_usage_set_dirty(su);
> + kunmap_atomic(kaddr);
> brelse(bh);
> }
> return ret;
> --
>

> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bug...@googlegroups.com.

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[Ryusuke Konishi]

The bugfix patch for this issue has already been merged into mainline,
but its "Reported-by" tag looks to be broken.
It is the patch titled below:

#syz fix: nilfs2: fix nilfs_sufile_mark_dirty() not set segment usage as dirty

Ryusuke Konishi