Message-ID: <CAB3wodfX_aO+ZLULPxnXbFM8UK4F30Q6pHaVn6U4X4TdiOzYbw@mail.gmail.com>
Date:   Mon, 13 Nov 2023 15:27:54 +0000
From:   Phillip Lougher <phillip.lougher@...il.com>
To:     syzbot <syzbot+604424eb051c2f696163@...kaller.appspotmail.com>
Cc:     akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, phillip@...ashfs.org.uk,
        squashfs-devel@...ts.sourceforge.net,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [squashfs?] KASAN: slab-out-of-bounds Write in
 squashfs_readahead (2)

On Sun, Nov 12, 2023 at 5:32 AM syzbot
<syzbot+604424eb051c2f696163@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    13d88ac54ddd Merge tag 'vfs-6.7.fsid' of git://git.kernel...
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=121965ef680000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
> dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12b40c7b680000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10f691ef680000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/9e81dc4903c2/disk-13d88ac5.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/f40fd7326b3f/vmlinux-13d88ac5.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2f399cd6ff7d/bzImage-13d88ac5.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/8e127c645a04/mount_0.gz
>
> The issue was bisected to:
>
> commit f268eedddf3595e85f8883dc50aed29654785696
> Author: Phillip Lougher <phillip@...ashfs.org.uk>
> Date:   Sat Jun 11 03:21:32 2022 +0000
>
>     squashfs: extend "page actor" to handle missing pages

Fixed the issue, and will send a patch shortly.

Phillip

>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1252b717680000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=1152b717680000
> console output: https://syzkaller.appspot.com/x/log.txt?x=1652b717680000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+604424eb051c2f696163@...kaller.appspotmail.com
> Fixes: f268eedddf35 ("squashfs: extend "page actor" to handle missing pages")
>
> SQUASHFS error: Unable to read metadata cache entry [6fa]
> SQUASHFS error: Unable to read metadata cache entry [6fa]
> SQUASHFS error: Unable to read metadata cache entry [6fa]
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in __readahead_batch include/linux/pagemap.h:1364 [inline]
> BUG: KASAN: slab-out-of-bounds in squashfs_readahead+0x9a6/0x20d0 fs/squashfs/file.c:569
> Write of size 8 at addr ffff88801e393648 by task syz-executor100/5067
>
> CPU: 1 PID: 5067 Comm: syz-executor100 Not tainted 6.6.0-syzkaller-15156-g13d88ac54ddd #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
>  print_address_description mm/kasan/report.c:364 [inline]
>  print_report+0x163/0x540 mm/kasan/report.c:475
>  kasan_report+0x142/0x170 mm/kasan/report.c:588
>  __readahead_batch include/linux/pagemap.h:1364 [inline]
>  squashfs_readahead+0x9a6/0x20d0 fs/squashfs/file.c:569
>  read_pages+0x183/0x830 mm/readahead.c:160
>  page_cache_ra_unbounded+0x68e/0x7c0 mm/readahead.c:269
>  page_cache_sync_readahead include/linux/pagemap.h:1266 [inline]
>  filemap_get_pages+0x49c/0x2080 mm/filemap.c:2497
>  filemap_read+0x42b/0x10b0 mm/filemap.c:2593
>  __kernel_read+0x425/0x8b0 fs/read_write.c:428
>  integrity_kernel_read+0xb0/0xf0 security/integrity/iint.c:221
>  ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
>  ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
>  ima_calc_file_hash+0xad1/0x1b30 security/integrity/ima/ima_crypto.c:573
>  ima_collect_measurement+0x554/0xb30 security/integrity/ima/ima_api.c:290
>  process_measurement+0x1373/0x21c0 security/integrity/ima/ima_main.c:359
>  ima_file_check+0xf1/0x170 security/integrity/ima/ima_main.c:557
>  do_open fs/namei.c:3624 [inline]
>  path_openat+0x2893/0x3280 fs/namei.c:3779
>  do_filp_open+0x234/0x490 fs/namei.c:3809
>  do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
>  do_sys_open fs/open.c:1455 [inline]
>  __do_sys_open fs/open.c:1463 [inline]
>  __se_sys_open fs/open.c:1459 [inline]
>  __x64_sys_open+0x225/0x270 fs/open.c:1459
>  do_syscall_x64 arch/x86/entry/common.c:51 [inline]
>  do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
>  entry_SYSCALL_64_after_hwframe+0x63/0x6b
> RIP: 0033:0x7f0e73d6c5f9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 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:00007ffd516ff158 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
> RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007f0e73d6c5f9
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200000c0
> RBP: 00007f0e73ddf610 R08: 0000000000000225 R09: 0000000000000000
> R10: 00007ffd516ff020 R11: 0000000000000246 R12: 0000000000000001
> R13: 00007ffd516ff328 R14: 0000000000000001 R15: 0000000000000001
>  </TASK>
>
> Allocated by task 5067:
>  kasan_save_stack mm/kasan/common.c:45 [inline]
>  kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
>  ____kasan_kmalloc mm/kasan/common.c:374 [inline]
>  __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
>  kasan_kmalloc include/linux/kasan.h:198 [inline]
>  __do_kmalloc_node mm/slab_common.c:1007 [inline]
>  __kmalloc+0xb9/0x230 mm/slab_common.c:1020
>  kmalloc_array include/linux/slab.h:637 [inline]
>  squashfs_readahead+0x30c/0x20d0 fs/squashfs/file.c:552
>  read_pages+0x183/0x830 mm/readahead.c:160
>  page_cache_ra_unbounded+0x68e/0x7c0 mm/readahead.c:269
>  page_cache_sync_readahead include/linux/pagemap.h:1266 [inline]
>  filemap_get_pages+0x49c/0x2080 mm/filemap.c:2497
>  filemap_read+0x42b/0x10b0 mm/filemap.c:2593
>  __kernel_read+0x425/0x8b0 fs/read_write.c:428
>  integrity_kernel_read+0xb0/0xf0 security/integrity/iint.c:221
>  ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
>  ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
>  ima_calc_file_hash+0xad1/0x1b30 security/integrity/ima/ima_crypto.c:573
>  ima_collect_measurement+0x554/0xb30 security/integrity/ima/ima_api.c:290
>  process_measurement+0x1373/0x21c0 security/integrity/ima/ima_main.c:359
>  ima_file_check+0xf1/0x170 security/integrity/ima/ima_main.c:557
>  do_open fs/namei.c:3624 [inline]
>  path_openat+0x2893/0x3280 fs/namei.c:3779
>  do_filp_open+0x234/0x490 fs/namei.c:3809
>  do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
>  do_sys_open fs/open.c:1455 [inline]
>  __do_sys_open fs/open.c:1463 [inline]
>  __se_sys_open fs/open.c:1459 [inline]
>  __x64_sys_open+0x225/0x270 fs/open.c:1459
>  do_syscall_x64 arch/x86/entry/common.c:51 [inline]
>  do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
>  entry_SYSCALL_64_after_hwframe+0x63/0x6b
>
> The buggy address belongs to the object at ffff88801e393640
>  which belongs to the cache kmalloc-8 of size 8
> The buggy address is located 0 bytes to the right of
>  allocated 8-byte region [ffff88801e393640, ffff88801e393648)
>
> The buggy address belongs to the physical page:
> page:ffffea000078e4c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88801e393230 pfn:0x1e393
> anon flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
> page_type: 0xffffffff()
> raw: 00fff00000000800 ffff888012c41280 0000000000000000 dead000000000001
> raw: ffff88801e393230 0000000080660063 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, tgid 1 (swapper/0), ts 10649202635, free_ts 9358727270
>  set_page_owner include/linux/page_owner.h:31 [inline]
>  post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1537
>  prep_new_page mm/page_alloc.c:1544 [inline]
>  get_page_from_freelist+0x339a/0x3530 mm/page_alloc.c:3312
>  __alloc_pages+0x255/0x670 mm/page_alloc.c:4568
>  alloc_pages_mpol+0x3de/0x640 mm/mempolicy.c:2133
>  alloc_slab_page+0x6a/0x160 mm/slub.c:1870
>  allocate_slab mm/slub.c:2017 [inline]
>  new_slab+0x84/0x2f0 mm/slub.c:2070
>  ___slab_alloc+0xc85/0x1310 mm/slub.c:3223
>  __slab_alloc mm/slub.c:3322 [inline]
>  __slab_alloc_node mm/slub.c:3375 [inline]
>  slab_alloc_node mm/slub.c:3468 [inline]
>  __kmem_cache_alloc_node+0x21d/0x300 mm/slub.c:3517
>  __do_kmalloc_node mm/slab_common.c:1006 [inline]
>  __kmalloc_node_track_caller+0xa5/0x230 mm/slab_common.c:1027
>  kstrdup+0x3a/0x70 mm/util.c:62
>  __kernfs_new_node+0x9d/0x870 fs/kernfs/dir.c:611
>  kernfs_new_node+0x99/0x170 fs/kernfs/dir.c:679
>  kernfs_create_link+0xa5/0x1f0 fs/kernfs/symlink.c:39
>  sysfs_do_create_link_sd+0x85/0x100 fs/sysfs/symlink.c:44
>  device_create_sys_dev_entry+0x10f/0x170 drivers/base/core.c:3451
>  device_add+0x8cf/0xd30 drivers/base/core.c:3595
> page last free stack trace:
>  reset_page_owner include/linux/page_owner.h:24 [inline]
>  free_pages_prepare mm/page_alloc.c:1137 [inline]
>  free_unref_page_prepare+0x92a/0xa50 mm/page_alloc.c:2347
>  free_unref_page+0x37/0x3f0 mm/page_alloc.c:2487
>  vfree+0x186/0x2e0 mm/vmalloc.c:2842
>  delayed_vfree_work+0x56/0x80 mm/vmalloc.c:2763
>  process_one_work kernel/workqueue.c:2630 [inline]
>  process_scheduled_works+0x90f/0x1400 kernel/workqueue.c:2703
>  worker_thread+0xa5f/0xff0 kernel/workqueue.c:2784
>  kthread+0x2d3/0x370 kernel/kthread.c:388
>  ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
>
> Memory state around the buggy address:
>  ffff88801e393500: 00 fc fc fc fc fa fc fc fc fc 05 fc fc fc fc 05
>  ffff88801e393580: fc fc fc fc 00 fc fc fc fc 05 fc fc fc fc fa fc
> >ffff88801e393600: fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc
>                                               ^
>  ffff88801e393680: fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc
>  ffff88801e393700: fc 00 fc fc fc fc fb fc fc fc fc 00 fc fc fc fc
> ==================================================================
>
>
> ---
> 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.
> 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
>

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