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Date:   Mon, 25 Sep 2023 17:50:46 -0700
Message-ID: <00000000000021e24406063877ff@google.com>
Subject: [syzbot] [overlayfs?] KASAN: invalid-free in ovl_copy_up_one
From:   syzbot <syzbot+477d8d8901756d1cbba1@syzkaller.appspotmail.com>
To:     amir73il@gmail.com, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org,
        miklos@szeredi.hu, syzkaller-bugs@googlegroups.com
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Hello,

syzbot found the following issue on:

HEAD commit:    940fcc189c51 Add linux-next specific files for 20230921
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=158b9424680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1f140ae6e669ac24
dashboard link: https://syzkaller.appspot.com/bug?extid=477d8d8901756d1cbba1
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=120e0dba680000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12f3767a680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b8921b235c24/disk-940fcc18.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c80a9f6bcdd4/vmlinux-940fcc18.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ed10a4df6950/bzImage-940fcc18.xz

The issue was bisected to:

commit 44ef23e481b02df2f17599a24f81cf0045dc5256
Author: Amir Goldstein <amir73il@gmail.com>
Date:   Wed Aug 16 13:47:59 2023 +0000

    ovl: do not encode lower fh with upper sb_writers held

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1364cda6680000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=10e4cda6680000
console output: https://syzkaller.appspot.com/x/log.txt?x=1764cda6680000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+477d8d8901756d1cbba1@syzkaller.appspotmail.com
Fixes: 44ef23e481b0 ("ovl: do not encode lower fh with upper sb_writers held")

RAX: ffffffffffffffda RBX: 00007ffd8d25ca30 RCX: 00007f15a9d353e9
RDX: 00007f15a9d344b0 RSI: 00007ffd8d25ca30 RDI: 0000000020000200
RBP: 0000000000000002 R08: 00007ffd8d25c7a6 R09: 00007ffd8d2d51a0
R10: 0000000000000002 R11: 0000000000000246 R12: 00007ffd8d25ca2c
R13: 00007ffd8d25ca70 R14: 00007ffd8d25ca50 R15: 0000000000000002
 </TASK>
==================================================================
BUG: KASAN: invalid-free in slab_free mm/slub.c:3809 [inline]
BUG: KASAN: invalid-free in __kmem_cache_free+0xb8/0x2d0 mm/slub.c:3822
Free of addr ffff888078b14650 by task syz-executor360/5060

CPU: 0 PID: 5060 Comm: syz-executor360 Not tainted 6.6.0-rc2-next-20230921-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xc4/0x620 mm/kasan/report.c:475
 kasan_report_invalid_free+0xab/0xd0 mm/kasan/report.c:550
 ____kasan_slab_free+0x1a0/0x1b0 mm/kasan/common.c:216
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1800 [inline]
 slab_free_freelist_hook+0x114/0x1e0 mm/slub.c:1826
 slab_free mm/slub.c:3809 [inline]
 __kmem_cache_free+0xb8/0x2d0 mm/slub.c:3822
 ovl_do_copy_up fs/overlayfs/copy_up.c:973 [inline]
 ovl_copy_up_one+0x15ac/0x3250 fs/overlayfs/copy_up.c:1137
 ovl_copy_up_flags+0x189/0x200 fs/overlayfs/copy_up.c:1192
 ovl_nlink_start+0x391/0x470 fs/overlayfs/util.c:1144
 ovl_do_remove+0x16d/0xd50 fs/overlayfs/dir.c:893
 vfs_unlink+0x2f1/0x900 fs/namei.c:4313
 do_unlinkat+0x3da/0x6d0 fs/namei.c:4379
 __do_sys_unlink fs/namei.c:4427 [inline]
 __se_sys_unlink fs/namei.c:4425 [inline]
 __x64_sys_unlink+0xc8/0x110 fs/namei.c:4425
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f15a9d353e9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 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:00007ffd8d25ca08 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00007ffd8d25ca30 RCX: 00007f15a9d353e9
RDX: 00007f15a9d344b0 RSI: 00007ffd8d25ca30 RDI: 0000000020000200
RBP: 0000000000000002 R08: 00007ffd8d25c7a6 R09: 00007ffd8d2d51a0
R10: 0000000000000002 R11: 0000000000000246 R12: 00007ffd8d25ca2c
R13: 00007ffd8d25ca70 R14: 00007ffd8d25ca50 R15: 0000000000000002
 </TASK>

Allocated by task 5060:
 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 __kasan_slab_alloc+0x81/0x90 mm/kasan/common.c:328
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook mm/slab.h:762 [inline]
 slab_alloc_node mm/slub.c:3478 [inline]
 slab_alloc mm/slub.c:3486 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3493 [inline]
 kmem_cache_alloc_lru+0x215/0x670 mm/slub.c:3509
 __d_alloc+0x32/0xac0 fs/dcache.c:1768
 d_alloc+0x4e/0x220 fs/dcache.c:1848
 lookup_one_qstr_excl+0xc7/0x180 fs/namei.c:1604
 do_unlinkat+0x294/0x6d0 fs/namei.c:4365
 __do_sys_unlink fs/namei.c:4427 [inline]
 __se_sys_unlink fs/namei.c:4425 [inline]
 __x64_sys_unlink+0xc8/0x110 fs/namei.c:4425
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Last potentially related work creation:
 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xbc/0xd0 mm/kasan/generic.c:492
 __call_rcu_common.constprop.0+0x9a/0x790 kernel/rcu/tree.c:2653
 dentry_free+0xc2/0x160 fs/dcache.c:377
 __dentry_kill+0x4c1/0x640 fs/dcache.c:621
 dentry_kill fs/dcache.c:745 [inline]
 dput+0x6de/0xf80 fs/dcache.c:913
 handle_mounts fs/namei.c:1554 [inline]
 step_into+0x1192/0x2230 fs/namei.c:1839
 walk_component+0xfc/0x5a0 fs/namei.c:2007
 lookup_last fs/namei.c:2458 [inline]
 path_lookupat+0x17f/0x770 fs/namei.c:2482
 filename_lookup+0x1e7/0x5b0 fs/namei.c:2511
 vfs_statx+0x160/0x430 fs/stat.c:240
 vfs_fstatat+0xb3/0x140 fs/stat.c:295
 __do_sys_newfstatat+0x98/0x110 fs/stat.c:459
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888078b145e0
 which belongs to the cache dentry of size 312
The buggy address is located 112 bytes inside of
 312-byte region [ffff888078b145e0, ffff888078b14718)

The buggy address belongs to the physical page:
page:ffffea0001e2c500 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x78b14
head:ffffea0001e2c500 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
ksm flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff88814000a8c0 ffffea0001e2d080 dead000000000003
raw: 0000000000000000 0000000000150015 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Reclaimable, gfp_mask 0xd20d0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_RECLAIMABLE), pid 4515, tgid 4515 (udevd), ts 47959600386, free_ts 28011797989
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2cf/0x340 mm/page_alloc.c:1530
 prep_new_page mm/page_alloc.c:1537 [inline]
 get_page_from_freelist+0xf17/0x2e50 mm/page_alloc.c:3200
 __alloc_pages+0x1d0/0x4a0 mm/page_alloc.c:4456
 alloc_pages+0x1a9/0x270 mm/mempolicy.c:2305
 alloc_slab_page mm/slub.c:1870 [inline]
 allocate_slab+0x251/0x380 mm/slub.c:2017
 new_slab mm/slub.c:2070 [inline]
 ___slab_alloc+0x8c7/0x1580 mm/slub.c:3223
 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3322
 __slab_alloc_node mm/slub.c:3375 [inline]
 slab_alloc_node mm/slub.c:3468 [inline]
 slab_alloc mm/slub.c:3486 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3493 [inline]
 kmem_cache_alloc_lru+0x4e1/0x670 mm/slub.c:3509
 __d_alloc+0x32/0xac0 fs/dcache.c:1768
 d_alloc+0x4e/0x220 fs/dcache.c:1848
 d_alloc_parallel+0xe9/0x12d0 fs/dcache.c:2637
 lookup_open.isra.0+0xaa4/0x13b0 fs/namei.c:3401
 open_last_lookups fs/namei.c:3544 [inline]
 path_openat+0x931/0x29c0 fs/namei.c:3774
 do_filp_open+0x1de/0x430 fs/namei.c:3804
 do_sys_openat2+0x176/0x1e0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1448
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1130 [inline]
 free_unref_page_prepare+0x476/0xa40 mm/page_alloc.c:2342
 free_unref_page+0x33/0x3b0 mm/page_alloc.c:2435
 free_contig_range+0xb6/0x190 mm/page_alloc.c:6372
 destroy_args+0x7c9/0xa10 mm/debug_vm_pgtable.c:1028
 debug_vm_pgtable+0x1d79/0x3e00 mm/debug_vm_pgtable.c:1408
 do_one_initcall+0x11c/0x640 init/main.c:1232
 do_initcall_level init/main.c:1294 [inline]
 do_initcalls init/main.c:1310 [inline]
 do_basic_setup init/main.c:1329 [inline]
 kernel_init_freeable+0x5c2/0x8f0 init/main.c:1547
 kernel_init+0x1c/0x2a0 init/main.c:1437
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

Memory state around the buggy address:
 ffff888078b14500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888078b14580: 00 00 00 00 fc fc fc fc fc fc fc fc 00 00 00 00
>ffff888078b14600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff888078b14680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888078b14700: 00 00 00 fc fc fc fc fc fc fc fc 00 00 00 00 00
==================================================================


---
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If the bug is already fixed, 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
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#syz dup: exact-subject-of-another-report

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#syz undup