Re: [syzbot] [bluetooth?] KMSAN: uninit-value in hci_rx_work

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    8cf0b93919e1 Linux 6.12-rc2
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=164bc707980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=981fe2ff8a1e457a
dashboard link: https://syzkaller.appspot.com/bug?extid=6ea290ba76d8c1eb1ac2
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=114bc707980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17b74327980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e6ae962426a8/disk-8cf0b939.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6965b62be377/vmlinux-8cf0b939.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1a0056895389/bzImage-8cf0b939.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6ea290ba76d8c1eb1ac2@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
BUG: KMSAN: uninit-value in hci_acldata_packet net/bluetooth/hci_core.c:3796 [inline]
BUG: KMSAN: uninit-value in hci_rx_work+0x1092/0x11f0 net/bluetooth/hci_core.c:4030
 hci_acldata_packet net/bluetooth/hci_core.c:3796 [inline]
 hci_rx_work+0x1092/0x11f0 net/bluetooth/hci_core.c:4030
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
 worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
 kthread+0x3e2/0x540 kernel/kthread.c:389
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4091 [inline]
 slab_alloc_node mm/slub.c:4134 [inline]
 kmem_cache_alloc_node_noprof+0x6bf/0xb80 mm/slub.c:4186
 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:587
 __alloc_skb+0x363/0x7b0 net/core/skbuff.c:678
 alloc_skb include/linux/skbuff.h:1322 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:493 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:487 [inline]
 vhci_write+0x127/0x900 drivers/bluetooth/hci_vhci.c:607
 new_sync_write fs/read_write.c:590 [inline]
 vfs_write+0xb28/0x1540 fs/read_write.c:683
 ksys_write+0x24f/0x4c0 fs/read_write.c:736
 __do_sys_write fs/read_write.c:748 [inline]
 __se_sys_write fs/read_write.c:745 [inline]
 __x64_sys_write+0x93/0xe0 fs/read_write.c:745
 x64_sys_call+0x306a/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 4565 Comm: kworker/u9:1 Not tainted 6.12.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: hci0 hci_rx_work
=====================================================


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