Subject: Re: [syzbot] KMSAN: uninit-value in hci_conn_request_evt

From: syzbot <[email-masked]>
Date: Sun, 02 Jan 2022 14:23:18 -0800

syzbot has found a reproducer for the following issue on:

HEAD commit:    81c325bbf94e kmsan: hooks: do not check memory in kmsan_in..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=103ea4c7b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2d8b9a11641dc9aa
dashboard link: https://syzkaller.appspot.com/bug?extid=8f84cf3ec5c288e779ef
compiler:       clang version 14.0.0 (/usr/local/google/src/llvm-git-monorepo 2b554920f11c8b763cd9ed9003f4e19b919b8e1f), GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10051b67b00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12148a3bb00000

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

=====================================================
BUG: KMSAN: uninit-value in hci_proto_connect_ind include/net/bluetooth/hci_core.h:1485 [inline]
BUG: KMSAN: uninit-value in hci_conn_request_evt+0x22b/0x13c0 net/bluetooth/hci_event.c:2827
 hci_proto_connect_ind include/net/bluetooth/hci_core.h:1485 [inline]
 hci_conn_request_evt+0x22b/0x13c0 net/bluetooth/hci_event.c:2827
 hci_event_packet+0x1452/0x23e0 net/bluetooth/hci_event.c:6360
 hci_rx_work+0x6a0/0xd00 net/bluetooth/hci_core.c:5084
 process_one_work+0xdb9/0x1820 kernel/workqueue.c:2298
 worker_thread+0x10bc/0x21f0 kernel/workqueue.c:2445
 kthread+0x721/0x850 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

Uninit was created at:
 slab_post_alloc_hook mm/slab.h:524 [inline]
 slab_alloc_node mm/slub.c:3251 [inline]
 __kmalloc_node_track_caller+0xe0c/0x1510 mm/slub.c:4974
 kmalloc_reserve net/core/skbuff.c:354 [inline]
 __alloc_skb+0x545/0xf90 net/core/skbuff.c:426
 alloc_skb include/linux/skbuff.h:1126 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:413 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:287 [inline]
 vhci_write+0x187/0x8f0 drivers/bluetooth/hci_vhci.c:407
 call_write_iter include/linux/fs.h:2162 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x1318/0x2030 fs/read_write.c:590
 ksys_write+0x28b/0x510 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0xdb/0x120 fs/read_write.c:652
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x44/0xae

CPU: 1 PID: 43 Comm: kworker/u5:0 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci0 hci_rx_work
=====================================================