Message-ID: <68c2c045-c0d4-4896-b3e5-ba3d767f7110@kernel.org>
Date: Wed, 28 May 2025 15:28:43 +0800
From: Chao Yu <chao@...nel.org>
To: syzbot <syzbot+1fa48dc6faf1ff972d7d@...kaller.appspotmail.com>,
 jaegeuk@...nel.org, linux-f2fs-devel@...ts.sourceforge.net,
 linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Cc: chao@...nel.org
Subject: Re: [syzbot] [f2fs?] KASAN: slab-out-of-bounds Read in
 build_sit_entries

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/chao/linux.git bugfix/syzbot

On 5/26/25 20:20, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    176e917e010c Add linux-next specific files for 20250523
> git tree:       linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=148c2170580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=e7902c752bef748
> dashboard link: https://syzkaller.appspot.com/bug?extid=1fa48dc6faf1ff972d7d
> compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=128bead4580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=100288e8580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/5f7692c642fa/disk-176e917e.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/057a442d42d0/vmlinux-176e917e.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/8f8ebdb4dd96/bzImage-176e917e.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/81e56747f56a/mount_2.gz
>   fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=138f59f4580000)
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+1fa48dc6faf1ff972d7d@...kaller.appspotmail.com
> 
> loop0: detected capacity change from 0 to 262144
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in sanity_check_valid_blocks fs/f2fs/segment.h:385 [inline]
> BUG: KASAN: slab-out-of-bounds in build_sit_entries+0x1b0c/0x1f80 fs/f2fs/segment.c:5060
> Read of size 4 at addr ffff888024798a20 by task syz-executor138/5840
> 
> CPU: 0 UID: 0 PID: 5840 Comm: syz-executor138 Not tainted 6.15.0-rc7-next-20250523-syzkaller #0 PREEMPT(full) 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
>  print_address_description mm/kasan/report.c:408 [inline]
>  print_report+0xd2/0x2b0 mm/kasan/report.c:521
>  kasan_report+0x118/0x150 mm/kasan/report.c:634
>  sanity_check_valid_blocks fs/f2fs/segment.h:385 [inline]
>  build_sit_entries+0x1b0c/0x1f80 fs/f2fs/segment.c:5060
>  f2fs_build_segment_manager+0x3112/0x49f0 fs/f2fs/segment.c:5707
>  f2fs_fill_super+0x45bc/0x6c80 fs/f2fs/super.c:4754
>  mount_bdev+0x211/0x2c0 fs/super.c:1736
>  legacy_get_tree+0xfd/0x1a0 fs/fs_context.c:666
>  vfs_get_tree+0x92/0x2b0 fs/super.c:1802
>  do_new_mount+0x24a/0xa40 fs/namespace.c:3869
>  do_mount fs/namespace.c:4206 [inline]
>  __do_sys_mount fs/namespace.c:4417 [inline]
>  __se_sys_mount+0x317/0x410 fs/namespace.c:4394
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7ff3b36f7e6a
> Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007ffc20c3a528 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007ffc20c3a540 RCX: 00007ff3b36f7e6a
> RDX: 0000200000020440 RSI: 0000200000020480 RDI: 00007ffc20c3a540
> RBP: 0000200000020480 R08: 00007ffc20c3a580 R09: 0000000000020419
> R10: 0000000000000000 R11: 0000000000000286 R12: 0000200000020440
> R13: 00007ffc20c3a580 R14: 0000000000000003 R15: 0000000000000000
>  </TASK>
> 
> Allocated by task 5840:
>  kasan_save_stack mm/kasan/common.c:47 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
>  poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
>  kasan_kmalloc include/linux/kasan.h:260 [inline]
>  __do_kmalloc_node mm/slub.c:4327 [inline]
>  __kvmalloc_node_noprof+0x30d/0x5f0 mm/slub.c:5014
>  f2fs_kvmalloc fs/f2fs/f2fs.h:3527 [inline]
>  f2fs_kvzalloc fs/f2fs/f2fs.h:3533 [inline]
>  build_sit_info fs/f2fs/segment.c:4779 [inline]
>  f2fs_build_segment_manager+0x1485/0x49f0 fs/f2fs/segment.c:5696
>  f2fs_fill_super+0x45bc/0x6c80 fs/f2fs/super.c:4754
>  mount_bdev+0x211/0x2c0 fs/super.c:1736
>  legacy_get_tree+0xfd/0x1a0 fs/fs_context.c:666
>  vfs_get_tree+0x92/0x2b0 fs/super.c:1802
>  do_new_mount+0x24a/0xa40 fs/namespace.c:3869
>  do_mount fs/namespace.c:4206 [inline]
>  __do_sys_mount fs/namespace.c:4417 [inline]
>  __se_sys_mount+0x317/0x410 fs/namespace.c:4394
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> The buggy address belongs to the object at ffff888024798000
>  which belongs to the cache kmalloc-4k of size 4096
> The buggy address is located 0 bytes to the right of
>  allocated 2592-byte region [ffff888024798000, ffff888024798a20)
> 
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x24798
> head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
> flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
> page_type: f5(slab)
> raw: 00fff00000000040 ffff88801a442140 dead000000000122 0000000000000000
> raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
> head: 00fff00000000040 ffff88801a442140 dead000000000122 0000000000000000
> head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
> head: 00fff00000000003 ffffea000091e601 00000000ffffffff 00000000ffffffff
> head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5840, tgid 5840 (syz-executor138), ts 92190833917, free_ts 90155481941
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
>  prep_new_page mm/page_alloc.c:1712 [inline]
>  get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
>  __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
>  alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
>  alloc_slab_page mm/slub.c:2450 [inline]
>  allocate_slab+0x8a/0x3b0 mm/slub.c:2618
>  new_slab mm/slub.c:2672 [inline]
>  ___slab_alloc+0xbfc/0x1480 mm/slub.c:3858
>  __slab_alloc mm/slub.c:3948 [inline]
>  __slab_alloc_node mm/slub.c:4023 [inline]
>  slab_alloc_node mm/slub.c:4184 [inline]
>  __do_kmalloc_node mm/slub.c:4326 [inline]
>  __kvmalloc_node_noprof+0x429/0x5f0 mm/slub.c:5014
>  f2fs_kvmalloc fs/f2fs/f2fs.h:3527 [inline]
>  f2fs_kvzalloc fs/f2fs/f2fs.h:3533 [inline]
>  build_sit_info fs/f2fs/segment.c:4779 [inline]
>  f2fs_build_segment_manager+0x1485/0x49f0 fs/f2fs/segment.c:5696
>  f2fs_fill_super+0x45bc/0x6c80 fs/f2fs/super.c:4754
>  mount_bdev+0x211/0x2c0 fs/super.c:1736
>  legacy_get_tree+0xfd/0x1a0 fs/fs_context.c:666
>  vfs_get_tree+0x92/0x2b0 fs/super.c:1802
>  do_new_mount+0x24a/0xa40 fs/namespace.c:3869
>  do_mount fs/namespace.c:4206 [inline]
>  __do_sys_mount fs/namespace.c:4417 [inline]
>  __se_sys_mount+0x317/0x410 fs/namespace.c:4394
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> page last free pid 5833 tgid 5833 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  free_pages_prepare mm/page_alloc.c:1248 [inline]
>  __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
>  discard_slab mm/slub.c:2716 [inline]
>  __put_partials+0x161/0x1c0 mm/slub.c:3185
>  put_cpu_partial+0x17c/0x250 mm/slub.c:3260
>  __slab_free+0x2f7/0x400 mm/slub.c:4512
>  qlink_free mm/kasan/quarantine.c:163 [inline]
>  qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
>  kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
>  __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329
>  kasan_slab_alloc include/linux/kasan.h:250 [inline]
>  slab_post_alloc_hook mm/slub.c:4147 [inline]
>  slab_alloc_node mm/slub.c:4196 [inline]
>  kmem_cache_alloc_node_noprof+0x1bb/0x3c0 mm/slub.c:4248
>  __alloc_skb+0x112/0x2d0 net/core/skbuff.c:660
>  alloc_skb_fclone include/linux/skbuff.h:1386 [inline]
>  tcp_stream_alloc_skb+0x3d/0x340 net/ipv4/tcp.c:894
>  tcp_sendmsg_locked+0x115c/0x5550 net/ipv4/tcp.c:1204
>  tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1400
>  sock_sendmsg_nosec net/socket.c:712 [inline]
>  __sock_sendmsg+0x19c/0x270 net/socket.c:727
>  sock_write_iter+0x258/0x330 net/socket.c:1131
>  new_sync_write fs/read_write.c:593 [inline]
>  vfs_write+0x548/0xa90 fs/read_write.c:686
>  ksys_write+0x145/0x250 fs/read_write.c:738
> 
> Memory state around the buggy address:
>  ffff888024798900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff888024798980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> ffff888024798a00: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
>                                ^
>  ffff888024798a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff888024798b00: 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@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> 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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