Subject: KMSAN: uninit-value in hci_event_packet (2)

From: syzbot <[email-masked]>
Date: Mon, 21 Sep 2020 07:51:21 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    c5a13b33 kmsan: clang-format core
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=1622db65900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=20f149ad694ba4be
dashboard link: https://syzkaller.appspot.com/bug?extid=54f68ac8e259a8af4f12
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
userspace arch: i386

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

=====================================================
BUG: KMSAN: uninit-value in hci_conn_hash_lookup_ba include/net/bluetooth/hci_core.h:960 [inline]
BUG: KMSAN: uninit-value in hci_conn_complete_evt net/bluetooth/hci_event.c:2579 [inline]
BUG: KMSAN: uninit-value in hci_event_packet+0x1438/0x39e30 net/bluetooth/hci_event.c:6058
CPU: 1 PID: 8513 Comm: kworker/u5:1 Not tainted 5.9.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci4 hci_rx_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x21c/0x280 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:122
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:219
 hci_conn_hash_lookup_ba include/net/bluetooth/hci_core.h:960 [inline]
 hci_conn_complete_evt net/bluetooth/hci_event.c:2579 [inline]
 hci_event_packet+0x1438/0x39e30 net/bluetooth/hci_event.c:6058
 hci_rx_work+0x745/0xd20 net/bluetooth/hci_core.c:4889
 process_one_work+0x1688/0x2140 kernel/workqueue.c:2269
 worker_thread+0x10bc/0x2730 kernel/workqueue.c:2415
 kthread+0x551/0x590 kernel/kthread.c:293
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:143 [inline]
 kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:126
 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:80
 slab_alloc_node mm/slub.c:2907 [inline]
 __kmalloc_node_track_caller+0x9aa/0x12f0 mm/slub.c:4511
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0x35f/0xb30 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1094 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:389 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:165 [inline]
 vhci_write+0x18a/0x890 drivers/bluetooth/hci_vhci.c:285
 call_write_iter include/linux/fs.h:1882 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0xfa8/0x1860 fs/read_write.c:578
 ksys_write+0x275/0x500 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write+0x92/0xb0 fs/read_write.c:640
 __ia32_sys_write+0x4a/0x70 fs/read_write.c:640
 do_syscall_32_irqs_on arch/x86/entry/common.c:80 [inline]
 __do_fast_syscall_32+0x129/0x180 arch/x86/entry/common.c:139
 do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:162
 do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:205
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
=====================================================

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