KMSAN: uninit-value in hci_cmd_timeout

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    686a4f77 kmsan: don't compile memmove
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=15b019d9e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e10654781bc1f11c
dashboard link: https://syzkaller.appspot.com/bug?extid=d5eabae89ae62371887f
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+d5eabae89ae62371887f@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
BUG: KMSAN: uninit-value in hci_cmd_timeout+0x2bd/0x2d0 net/bluetooth/hci_core.c:2637
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events hci_cmd_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x220 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 hci_cmd_timeout+0x2bd/0x2d0 net/bluetooth/hci_core.c:2637
 process_one_work+0x1552/0x1ef0 kernel/workqueue.c:2264
 worker_thread+0xef6/0x2450 kernel/workqueue.c:2410
 kthread+0x4b5/0x4f0 kernel/kthread.c:256
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:353

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82
 slab_alloc_node mm/slub.c:2774 [inline]
 slab_alloc mm/slub.c:2783 [inline]
 kmem_cache_alloc+0x711/0xd70 mm/slub.c:2788
 skb_clone+0x328/0x5d0 net/core/skbuff.c:1448
 hci_cmd_work+0x12f/0x4f0 net/bluetooth/hci_core.c:4527
 process_one_work+0x1552/0x1ef0 kernel/workqueue.c:2264
 worker_thread+0xef6/0x2450 kernel/workqueue.c:2410
 kthread+0x4b5/0x4f0 kernel/kthread.c:256
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:353
=====================================================


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