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From:   Ryusuke Konishi <konishi.ryusuke@gmail.com>
Date:   Sat, 24 Sep 2022 17:17:51 +0900
Message-ID: <CAKFNMoktjR4SupDqKaiR4MJgOXB69eiH6W5DgBbs2g1gUCfj4Q@mail.gmail.com>
Subject: Re: [syzbot] KASAN: use-after-free Read in nilfs_mdt_destroy
To:     syzbot <syzbot+3974efaf68c77533b42d@syzkaller.appspotmail.com>
Cc:     linux-kernel@vger.kernel.org, linux-nilfs@vger.kernel.org,
        syzkaller-bugs@googlegroups.com
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On Thu, Sep 22, 2022 at 1:11 AM Ryusuke Konishi wrote:
>
> On Thu, Sep 22, 2022 at 1:02 AM syzbot  wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    a335366bad13 Merge tag 'gpio-fixes-for-v6.0-rc6' of git://..
> > git tree:       upstream
> > console+strace: https://syzkaller.appspot.com/x/log.txt?x=13af94f8880000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=98a30118ec9215e9
> > dashboard link: https://syzkaller.appspot.com/bug?extid=3974efaf68c77533b42d
> > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11e17937080000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1570a75d080000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+3974efaf68c77533b42d@syzkaller.appspotmail.com
> >
> > ==================================================================
> > BUG: KASAN: use-after-free in nilfs_mdt_destroy+0x6f/0x80 fs/nilfs2/mdt.c:497
> > Read of size 8 at addr ffff888020124498 by task syz-executor134/3740
> >
> > CPU: 0 PID: 3740 Comm: syz-executor134 Not tainted 6.0.0-rc5-syzkaller-00094-ga335366bad13 #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
> > Call Trace:
> >  <TASK>
> >  __dump_stack lib/dump_stack.c:88 [inline]
> >  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
> >  print_address_description mm/kasan/report.c:317 [inline]
> >  print_report.cold+0x2ba/0x719 mm/kasan/report.c:433
> >  kasan_report+0xb1/0x1e0 mm/kasan/report.c:495
> >  nilfs_mdt_destroy+0x6f/0x80 fs/nilfs2/mdt.c:497
> >  nilfs_free_inode+0x3e/0x60 fs/nilfs2/super.c:168
> >  i_callback fs/inode.c:249 [inline]
> >  alloc_inode+0x13b/0x230 fs/inode.c:274
> >  new_inode_pseudo fs/inode.c:1019 [inline]
> >  new_inode+0x27/0x270 fs/inode.c:1047
> >  nilfs_new_inode+0xca/0x830 fs/nilfs2/inode.c:334
> >  nilfs_create fs/nilfs2/namei.c:85 [inline]
> >  nilfs_create+0xfe/0x300 fs/nilfs2/namei.c:75
> >  vfs_create fs/namei.c:3115 [inline]
> >  vfs_create+0x3e9/0x670 fs/namei.c:3101
> >  do_mknodat+0x3d9/0x530 fs/namei.c:3942
> >  __do_sys_mknodat fs/namei.c:3970 [inline]
> >  __se_sys_mknodat fs/namei.c:3967 [inline]
> >  __x64_sys_mknodat+0xaa/0xe0 fs/namei.c:3967
> >  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> >  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> > RIP: 0033:0x7f2443bec549
> > Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 c0 ff ff ff f7 d8 64 89 01 48
> > RSP: 002b:00007ffdd9390cc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000103
> > RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f2443bec549
> > RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000005
> > RBP: 00007ffdd9390cf0 R08: 0000000000000001 R09: 00007ffdd9390d00
> > R10: 0000000000000103 R11: 0000000000000246 R12: 0000000000000003
> > R13: 00007ffdd9390d30 R14: 00007ffdd9390d10 R15: 0000000000000009
> >  </TASK>
> >
> > Allocated by task 3621:
> >  kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
> >  kasan_set_track mm/kasan/common.c:45 [inline]
> >  set_alloc_info mm/kasan/common.c:437 [inline]
> >  ____kasan_kmalloc mm/kasan/common.c:516 [inline]
> >  ____kasan_kmalloc mm/kasan/common.c:475 [inline]
> >  __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:525
> >  kmalloc include/linux/slab.h:605 [inline]
> >  kzalloc include/linux/slab.h:733 [inline]
> >  nilfs_mdt_init+0x2c/0x1e0 fs/nilfs2/mdt.c:451
> >  nilfs_sufile_read+0x191/0x5a0 fs/nilfs2/sufile.c:1183
> >  nilfs_load_super_root fs/nilfs2/the_nilfs.c:130 [inline]
> >  load_nilfs+0x671/0x1330 fs/nilfs2/the_nilfs.c:269
> >  nilfs_fill_super fs/nilfs2/super.c:1059 [inline]
> >  nilfs_mount+0xa9a/0xfb0 fs/nilfs2/super.c:1317
> >  legacy_get_tree+0x105/0x220 fs/fs_context.c:610
> >  vfs_get_tree+0x89/0x2f0 fs/super.c:1530
> >  do_new_mount fs/namespace.c:3040 [inline]
> >  path_mount+0x1326/0x1e20 fs/namespace.c:3370
> >  do_mount fs/namespace.c:3383 [inline]
> >  __do_sys_mount fs/namespace.c:3591 [inline]
> >  __se_sys_mount fs/namespace.c:3568 [inline]
> >  __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
> >  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> >  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> >
> > The buggy address belongs to the object at ffff888020124400
> >  which belongs to the cache kmalloc-256 of size 256
> > The buggy address is located 152 bytes inside of
> >  256-byte region [ffff888020124400, ffff888020124500)
> >
> > The buggy address belongs to the physical page:
> > page:ffffea0000804900 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888020124a00 pfn:0x20124
> > head:ffffea0000804900 order:1 compound_mapcount:0 compound_pincount:0
> > flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
> > raw: 00fff00000010200 ffffea0001ff2508 ffff888011840708 ffff888011841b40
> > raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
> > page dumped because: kasan: bad access detected
> > page_owner tracks the page as allocated
> > page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 7456347523, free_ts 0
> >  prep_new_page mm/page_alloc.c:2532 [inline]
> >  get_page_from_freelist+0x109b/0x2ce0 mm/page_alloc.c:4283
> >  __alloc_pages+0x1c7/0x510 mm/page_alloc.c:5515
> >  alloc_page_interleave+0x1e/0x200 mm/mempolicy.c:2103
> >  alloc_pages+0x22f/0x270 mm/mempolicy.c:2265
> >  alloc_slab_page mm/slub.c:1824 [inline]
> >  allocate_slab+0x27e/0x3d0 mm/slub.c:1969
> >  new_slab mm/slub.c:2029 [inline]
> >  ___slab_alloc+0x7f1/0xe10 mm/slub.c:3031
> >  __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3118
> >  slab_alloc_node mm/slub.c:3209 [inline]
> >  slab_alloc mm/slub.c:3251 [inline]
> >  __kmalloc+0x32b/0x340 mm/slub.c:4420
> >  kmalloc include/linux/slab.h:605 [inline]
> >  kzalloc include/linux/slab.h:733 [inline]
> >  rh_call_control drivers/usb/core/hcd.c:514 [inline]
> >  rh_urb_enqueue drivers/usb/core/hcd.c:848 [inline]
> >  usb_hcd_submit_urb+0x661/0x2220 drivers/usb/core/hcd.c:1552
> >  usb_submit_urb+0x86d/0x1880 drivers/usb/core/urb.c:594
> >  usb_start_wait_urb+0x101/0x4b0 drivers/usb/core/message.c:58
> >  usb_internal_control_msg drivers/usb/core/message.c:102 [inline]
> >  usb_control_msg+0x31c/0x4a0 drivers/usb/core/message.c:153
> >  usb_get_string+0xbe/0x1b0 drivers/usb/core/message.c:843
> >  usb_string_sub+0xfa/0x3d0 drivers/usb/core/message.c:882
> >  usb_string+0x2fb/0x530 drivers/usb/core/message.c:987
> >  usb_cache_string+0x82/0x140 drivers/usb/core/message.c:1029
> > page_owner free stack trace missing
> >
> > Memory state around the buggy address:
> >  ffff888020124380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >  ffff888020124400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > >ffff888020124480: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
> >                             ^
> >  ffff888020124500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >  ffff888020124580: fc fc fc fc fc fc fc fc fc fc fc fc 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@googlegroups.com.
> >
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > syzbot can test patches for this issue, for details see:
> > https://goo.gl/tpsmEJ#testing-patches
>
> This looks like the same issue as the report [1]:
>
> [1] https://lore.kernel.org/all/CAFcO6XOcf1Jj2SeGt=jJV59wmhESeSKpfR0omdFRq+J9nD1vfQ@mail.gmail.com/T/#u
>
> The bug fix patch for this, is queued in the vfs tree with the title
> "fs: fix UAF/GPF bug in nilfs_mdt_destroy"  [2]:
>
> [2] https://lkml.kernel.org/r/20220816040859.659129-1-dzm91@hust.edu.cn
>
> It's in the latest linux-next as well.
> As the outlook for now, this patch would be merged to the mainline
> after Linux kernel 6.0 is released, and then backported to stable
> trees.
>
> Thanks,
> Ryusuke Konishi

#syz fix: fs: fix UAF/GPF bug in nilfs_mdt_destroy

According to the stack trace, the crash at nilfs_mdt_destroy() has
happened in the case where inode_init_alway() failed in alloc_inode().
This problem is exactly what the above patch fixes.

Ryusuke Konishi