syzbot

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BUG: KASAN: slab-use-after-free in force_devcd_write+0x317/0x340 drivers/bluetooth/hci_vhci.c:327
Read of size 8 at addr ffff88807b904800 by task syz.0.616/6682

CPU: 0 UID: 0 PID: 6682 Comm: syz.0.616 Not tainted 6.14.0-syzkaller-03576-g1e1ba8d23dae #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xc3/0x670 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 force_devcd_write+0x317/0x340 drivers/bluetooth/hci_vhci.c:327
 full_proxy_write+0x13c/0x200 fs/debugfs/file.c:398
 vfs_write+0x25c/0x1180 fs/read_write.c:682
 ksys_write+0x12a/0x240 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9f6a98d169
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc6a31c598 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9f6aba5fa0 RCX: 00007f9f6a98d169
RDX: 000000000000000e RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f9f6aa0e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9f6aba5fa0 R14: 00007f9f6aba5fa0 R15: 0000000000000003
 </TASK>

Allocated by task 5967:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
 kmalloc_noprof include/linux/slab.h:902 [inline]
 kzalloc_noprof include/linux/slab.h:1036 [inline]
 vhci_open+0x4c/0x430 drivers/bluetooth/hci_vhci.c:634
 misc_open+0x35a/0x420 drivers/char/misc.c:179
 chrdev_open+0x231/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x741/0x1c10 fs/open.c:956
 vfs_open+0x82/0x3f0 fs/open.c:1086
 do_open fs/namei.c:3845 [inline]
 path_openat+0x1e5e/0x2d40 fs/namei.c:4004
 do_filp_open+0x20b/0x470 fs/namei.c:4031
 do_sys_openat2+0x11b/0x1d0 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_openat fs/open.c:1460 [inline]
 __se_sys_openat fs/open.c:1455 [inline]
 __x64_sys_openat+0x174/0x210 fs/open.c:1455
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5967:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2376 [inline]
 slab_free mm/slub.c:4633 [inline]
 kfree+0x2b6/0x4d0 mm/slub.c:4832
 vhci_release+0xbb/0xf0 drivers/bluetooth/hci_vhci.c:670
 __fput+0x3ff/0xb70 fs/file_table.c:465
 task_work_run+0x14d/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xaea/0x2d60 kernel/exit.c:954
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1103
 get_signal+0x24cf/0x26a0 kernel/signal.c:3035
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x260 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88807b904800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 0 bytes inside of
 freed 1024-byte region [ffff88807b904800, ffff88807b904c00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b900
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b041dc0 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b041dc0 0000000000000000 dead000000000001
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0001ee4001 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
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 5621, tgid 5621 (dhcpcd), ts 54734097452, free_ts 54714856704
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1551
 prep_new_page mm/page_alloc.c:1559 [inline]
 get_page_from_freelist+0x10c4/0x34c0 mm/page_alloc.c:3477
 __alloc_frozen_pages_noprof+0x223/0x24d0 mm/page_alloc.c:4740
 alloc_pages_mpol+0x1fb/0x540 mm/mempolicy.c:2301
 alloc_slab_page mm/slub.c:2446 [inline]
 allocate_slab mm/slub.c:2610 [inline]
 new_slab+0x23c/0x330 mm/slub.c:2663
 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3849
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3939
 __slab_alloc_node mm/slub.c:4014 [inline]
 slab_alloc_node mm/slub.c:4175 [inline]
 __do_kmalloc_node mm/slub.c:4317 [inline]
 __kmalloc_noprof+0x2f2/0x510 mm/slub.c:4330
 kmalloc_noprof include/linux/slab.h:906 [inline]
 load_elf_phdrs+0x102/0x210 fs/binfmt_elf.c:532
 load_elf_binary+0x14b3/0x4f80 fs/binfmt_elf.c:960
 search_binary_handler fs/exec.c:1773 [inline]
 exec_binprm fs/exec.c:1805 [inline]
 bprm_execve fs/exec.c:1857 [inline]
 bprm_execve+0x8dd/0x1700 fs/exec.c:1833
 do_execveat_common.isra.0+0x4a5/0x610 fs/exec.c:1964
 do_execve fs/exec.c:2038 [inline]
 __do_sys_execve fs/exec.c:2114 [inline]
 __se_sys_execve fs/exec.c:2109 [inline]
 __x64_sys_execve+0x8e/0xb0 fs/exec.c:2109
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5620 tgid 5620 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_frozen_pages+0x6d8/0xf40 mm/page_alloc.c:2660
 discard_slab mm/slub.c:2707 [inline]
 __put_partials+0x16d/0x1c0 mm/slub.c:3176
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4e/0x120 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4138 [inline]
 slab_alloc_node mm/slub.c:4187 [inline]
 __do_kmalloc_node mm/slub.c:4317 [inline]
 __kmalloc_noprof+0x1d4/0x510 mm/slub.c:4330
 kmalloc_noprof include/linux/slab.h:906 [inline]
 tomoyo_realpath_from_path+0xc2/0x6e0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x274/0x460 security/tomoyo/file.c:822
 security_inode_getattr+0x116/0x290 security/security.c:2377
 vfs_getattr fs/stat.c:243 [inline]
 vfs_fstat+0x4b/0xd0 fs/stat.c:265
 vfs_fstatat+0xbc/0xf0 fs/stat.c:366
 __do_sys_newfstatat+0xa1/0x130 fs/stat.c:532
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88807b904700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88807b904780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88807b904800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88807b904880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807b904900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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