Message-ID: <00000000000054e4d10601e44b24@google.com>
Date:   Tue, 01 Aug 2023 15:44:48 -0700
From:   syzbot <syzbot+d285c6d0b23c6033d520@...kaller.appspotmail.com>
To:     aivazian.tigran@...il.com, brauner@...nel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: [syzbot] [bfs?] KASAN: null-ptr-deref Read in drop_buffers (2)

Hello,

syzbot found the following issue on:

HEAD commit:    ec8939156379 Add linux-next specific files for 20230731
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=161e3355a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dc839eae61644ed
dashboard link: https://syzkaller.appspot.com/bug?extid=d285c6d0b23c6033d520
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/084b7f2f7900/disk-ec893915.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/279a4144b6d9/vmlinux-ec893915.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a21cf5ede096/bzImage-ec893915.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d285c6d0b23c6033d520@...kaller.appspotmail.com

==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
BUG: KASAN: null-ptr-deref in buffer_busy fs/buffer.c:2902 [inline]
BUG: KASAN: null-ptr-deref in drop_buffers.constprop.0+0x99/0x510 fs/buffer.c:2914
Read of size 4 at addr 0000000000000060 by task syz-executor.1/17034

CPU: 1 PID: 17034 Comm: syz-executor.1 Not tainted 6.5.0-rc4-next-20230731-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 kasan_report+0xda/0x110 mm/kasan/report.c:588
 check_region_inline mm/kasan/generic.c:181 [inline]
 kasan_check_range+0xef/0x190 mm/kasan/generic.c:187
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
 buffer_busy fs/buffer.c:2902 [inline]
 drop_buffers.constprop.0+0x99/0x510 fs/buffer.c:2914
 try_to_free_buffers+0x21b/0x2d0 fs/buffer.c:2944
 filemap_release_folio+0x20f/0x270 mm/filemap.c:4089
 shrink_folio_list+0x28bc/0x3dc0 mm/vmscan.c:2068
 evict_folios+0x6bc/0x18f0 mm/vmscan.c:5181
 try_to_shrink_lruvec+0x769/0xb00 mm/vmscan.c:5357
 lru_gen_shrink_lruvec mm/vmscan.c:5494 [inline]
 shrink_lruvec+0x314/0x2980 mm/vmscan.c:6269
 shrink_node_memcgs mm/vmscan.c:6489 [inline]
 shrink_node+0x807/0x3730 mm/vmscan.c:6524
 shrink_zones mm/vmscan.c:6763 [inline]
 do_try_to_free_pages+0x3cf/0x1990 mm/vmscan.c:6825
 try_to_free_mem_cgroup_pages+0x36f/0x850 mm/vmscan.c:7140
 try_charge_memcg+0x460/0x1400 mm/memcontrol.c:2692
 obj_cgroup_charge_pages mm/memcontrol.c:3106 [inline]
 __memcg_kmem_charge_page+0x179/0x3d0 mm/memcontrol.c:3132
 __alloc_pages+0x1fc/0x4a0 mm/page_alloc.c:4529
 alloc_pages+0x1a9/0x270 mm/mempolicy.c:2292
 vm_area_alloc_pages mm/vmalloc.c:3059 [inline]
 __vmalloc_area_node mm/vmalloc.c:3135 [inline]
 __vmalloc_node_range+0xa6e/0x1540 mm/vmalloc.c:3316
 kvmalloc_node+0x14b/0x1a0 mm/util.c:629
 kvmalloc include/linux/slab.h:737 [inline]
 xt_alloc_table_info+0x3e/0xa0 net/netfilter/x_tables.c:1192
 do_replace net/ipv6/netfilter/ip6_tables.c:1139 [inline]
 do_ip6t_set_ctl+0x53c/0xbd0 net/ipv6/netfilter/ip6_tables.c:1636
 nf_setsockopt+0x87/0xe0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x12b/0x190 net/ipv6/ipv6_sockglue.c:1017
 udpv6_setsockopt+0x7d/0xc0 net/ipv6/udp.c:1690
 __sys_setsockopt+0x2ca/0x5b0 net/socket.c:2265
 __do_sys_setsockopt net/socket.c:2276 [inline]
 __se_sys_setsockopt net/socket.c:2273 [inline]
 __x64_sys_setsockopt+0xbd/0x150 net/socket.c:2273
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0509e7cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f050aba80c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f0509f9bf80 RCX: 00007f0509e7cae9
RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000003
RBP: 00007f0509ec847a R08: 00000000000003e0 R09: 0000000000000000
R10: 00000000200014c0 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f0509f9bf80 R15: 00007ffea4aa1d48
 </TASK>
==================================================================


---
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@...glegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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

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

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

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

Powered by blists - more mailing lists