Subject: [syzbot] [bluetooth?] KASAN: slab-out-of-bounds Read in create_monitor_event

From: syzbot <[email-masked]>
Date: Mon, 09 Oct 2023 03:29:45 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    f291209eca5e Merge tag 'net-6.6-rc5' of git://git.kernel.o..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11011862680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7a5682d32a74b423
dashboard link: https://syzkaller.appspot.com/bug?extid=c90849c50ed209d77689
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=14d8746e680000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1388dbae680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c35c46fb9748/disk-f291209e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f0cdf2349ddb/vmlinux-f291209e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2f4c7b7ed7c4/bzImage-f291209e.xz

The issue was bisected to:

commit dcda165706b9fbfd685898d46a6749d7d397e0c0
Author: Luiz Augusto von Dentz <[email-masked]>
Date:   Fri Sep 15 21:42:27 2023 +0000

    Bluetooth: hci_core: Fix build warnings

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1279df95680000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1179df95680000
console output: https://syzkaller.appspot.com/x/log.txt?x=1679df95680000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]
Fixes: dcda165706b9 ("Bluetooth: hci_core: Fix build warnings")

==================================================================
BUG: KASAN: slab-out-of-bounds in create_monitor_event+0x88d/0x930 net/bluetooth/hci_sock.c:491
Read of size 8 at addr ffff88801e5458c7 by task syz-executor191/5038

CPU: 0 PID: 5038 Comm: syz-executor191 Not tainted 6.6.0-rc4-syzkaller-00158-gf291209eca5e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
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+0x175/0x1b0 mm/kasan/report.c:588
 create_monitor_event+0x88d/0x930 net/bluetooth/hci_sock.c:491
 send_monitor_replay+0x7a/0x5d0 net/bluetooth/hci_sock.c:723
 hci_sock_bind+0x85c/0x1140 net/bluetooth/hci_sock.c:1387
 __sys_bind+0x23a/0x2e0 net/socket.c:1849
 __do_sys_bind net/socket.c:1860 [inline]
 __se_sys_bind net/socket.c:1858 [inline]
 __x64_sys_bind+0x7a/0x90 net/socket.c:1858
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fa90faa64f9
Code: 48 83 c4 28 c3 e8 17 19 00 00 0f 1f 80 00 00 00 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc6a6f17b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fa90faa64f9
RDX: 0000000000000006 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 0000000000000003 R08: 000000ff00ffb650 R09: 000000ff00ffb650
R10: 0000000000000000 R11: 0000000000000246 R12: 000055555604a370
R13: 0000000000000072 R14: 00007fa90fb2a5b0 R15: 0000000000000001
 </TASK>

Allocated by task 5038:
 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:1023 [inline]
 __kmalloc_node_track_caller+0xb6/0x230 mm/slab_common.c:1043
 kvasprintf+0xdf/0x190 lib/kasprintf.c:25
 kobject_set_name_vargs+0x61/0x120 lib/kobject.c:272
 dev_set_name+0xd5/0x120 drivers/base/core.c:3427
 hci_register_dev+0x153/0xa40 net/bluetooth/hci_core.c:2620
 __vhci_create_device drivers/bluetooth/hci_vhci.c:434 [inline]
 vhci_create_device+0x3ba/0x720 drivers/bluetooth/hci_vhci.c:475
 vhci_get_user drivers/bluetooth/hci_vhci.c:532 [inline]
 vhci_write+0x3c7/0x480 drivers/bluetooth/hci_vhci.c:612
 call_write_iter include/linux/fs.h:1956 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x782/0xaf0 fs/read_write.c:584
 ksys_write+0x1a0/0x2c0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88801e5458c0
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 2 bytes to the right of
 allocated 5-byte region [ffff88801e5458c0, ffff88801e5458c5)

The buggy address belongs to the physical page:
page:ffffea0000795140 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1e545
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff888012841280 ffffea00004db540 dead000000000002
raw: 0000000000000000 0000000000660066 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 0x12c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY), pid 25, tgid 25 (kdevtmpfs), ts 9275165846, free_ts 9274763750
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1536
 prep_new_page mm/page_alloc.c:1543 [inline]
 get_page_from_freelist+0x31db/0x3360 mm/page_alloc.c:3170
 __alloc_pages+0x255/0x670 mm/page_alloc.c:4426
 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+0x1af/0x270 mm/slub.c:3517
 __do_kmalloc_node mm/slab_common.c:1022 [inline]
 __kmalloc_node_track_caller+0xa5/0x230 mm/slab_common.c:1043
 kstrdup+0x3a/0x70 mm/util.c:62
 smack_inode_init_security+0x5ed/0x740 security/smack/smack_lsm.c:1046
 security_inode_init_security+0x1a1/0x470 security/security.c:1648
 shmem_mknod+0xc6/0x1d0 mm/shmem.c:3221
 vfs_mknod+0x308/0x350 fs/namei.c:3998
 handle_create drivers/base/devtmpfs.c:219 [inline]
 handle drivers/base/devtmpfs.c:384 [inline]
 devtmpfs_work_loop+0x95c/0x1030 drivers/base/devtmpfs.c:399
 devtmpfsd+0x48/0x50 drivers/base/devtmpfs.c:441
 kthread+0x2d3/0x370 kernel/kthread.c:388
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1136 [inline]
 free_unref_page_prepare+0x8c3/0x9f0 mm/page_alloc.c:2312
 free_unref_page+0x37/0x3f0 mm/page_alloc.c:2405
 mm_free_pgd kernel/fork.c:803 [inline]
 __mmdrop+0xb8/0x3d0 kernel/fork.c:919
 free_bprm+0x144/0x330 fs/exec.c:1492
 kernel_execve+0x8f5/0xa10 fs/exec.c:2026
 call_usermodehelper_exec_async+0x233/0x370 kernel/umh.c:110
 ret_from_fork+0x48/0x80 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:
 ffff88801e545780: 05 fc fc fc fc 05 fc fc fc fc 05 fc fc fc fc 05
 ffff88801e545800: fc fc fc fc 05 fc fc fc fc 00 fc fc fc fc 00 fc
>ffff88801e545880: fc fc fc 00 fc fc fc fc 05 fc fc fc fc 00 fc fc
                                           ^
 ffff88801e545900: fc fc 00 fc fc fc fc 00 fc fc fc fc 05 fc fc fc
 ffff88801e545980: fc 05 fc fc fc fc fa fc fc fc fc 00 fc fc fc fc
==================================================================

---
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