Re: KASAN: slab-out-of-bounds Read in default_write_copy_kernel

[syzbot]

syzbot has bisected this bug to:

commit 65766ee0bf7fe8b3be80e2e1c3ef54ad59b29476
Author: Takashi Iwai <tiwai@xxxxxxx>
Date:   Fri Nov 9 10:59:45 2018 +0000

    ALSA: oss: Use kvzalloc() for local buffer allocations

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11c3005d200000
start commit:   65766ee0 ALSA: oss: Use kvzalloc() for local buffer alloca..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=13c3005d200000
console output: https://syzkaller.appspot.com/x/log.txt?x=15c3005d200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=73e2bc0cb6463446
dashboard link: https://syzkaller.appspot.com/bug?extid=d4503ae45b65c5bc1194
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1789354d400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=162ebe2b400000

Reported-by: syzbot+d4503ae45b65c5bc1194@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 65766ee0 ("ALSA: oss: Use kvzalloc() for local buffer allocations")