syzbot

==================================================================
BUG: KASAN: null-ptr-deref in copy_to_user arch/x86/include/asm/uaccess.h:716 [inline]
BUG: KASAN: null-ptr-deref in snd_timer_user_read+0x510/0x700 sound/core/timer.c:2006
Read of size 32 at addr           (null) by task syzkaller300733/3329

CPU: 0 PID: 3329 Comm: syzkaller300733 Not tainted 4.9.77-g9c3804b #17
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801c912f9d8 ffffffff81d941c9 0000000000000000 0000000000000020
 0000000000000000 ffff8801c912fba0 ffff8801c8d4cf48 ffff8801c912fa20
 ffffffff8153df9e ffffffff82da5800 0000000000000286 4ffe2257e229b61c
Call Trace:
 [<ffffffff81d941c9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d941c9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8153df9e>] kasan_report_error mm/kasan/report.c:349 [inline]
 [<ffffffff8153df9e>] kasan_report+0x15e/0x360 mm/kasan/report.c:408
 [<ffffffff8153cac7>] check_memory_region_inline mm/kasan/kasan.c:318 [inline]
 [<ffffffff8153cac7>] check_memory_region+0x137/0x190 mm/kasan/kasan.c:325
 [<ffffffff8153cb31>] kasan_check_read+0x11/0x20 mm/kasan/kasan.c:330
 [<ffffffff82da5800>] copy_to_user arch/x86/include/asm/uaccess.h:716 [inline]
 [<ffffffff82da5800>] snd_timer_user_read+0x510/0x700 sound/core/timer.c:2006
 [<ffffffff8156c5c1>] do_loop_readv_writev.part.17+0x141/0x1e0 fs/read_write.c:714
 [<ffffffff81570430>] do_loop_readv_writev fs/read_write.c:880 [inline]
 [<ffffffff81570430>] do_readv_writev+0x520/0x750 fs/read_write.c:874
 [<ffffffff815706e4>] vfs_readv+0x84/0xc0 fs/read_write.c:898
 [<ffffffff81570806>] do_readv+0xe6/0x250 fs/read_write.c:924
 [<ffffffff81573cf7>] SYSC_readv fs/read_write.c:1011 [inline]
 [<ffffffff81573cf7>] SyS_readv+0x27/0x30 fs/read_write.c:1008
 [<ffffffff838b2c2e>] entry_SYSCALL_64_fastpath+0x29/0xe8
==================================================================
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 3329 Comm: syzkaller300733 Tainted: G    B           4.9.77-g9c3804b #17
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801c912f8f8 ffffffff81d941c9 ffffffff841970ff ffff8801c912f9d0
 0000000000000000 ffff8801c912fba0 ffff8801c8d4cf48 ffff8801c912f9c0
 ffffffff8142f3c1 0000000041b58ab3 ffffffff8418ab70 ffffffff8142f205
Call Trace:
 [<ffffffff81d941c9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d941c9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8142f3c1>] panic+0x1bc/0x3a8 kernel/panic.c:179
 [<ffffffff8153db00>] kasan_end_report+0x50/0x50 mm/kasan/report.c:176
 [<ffffffff8153dfa7>] kasan_report_error mm/kasan/report.c:356 [inline]
 [<ffffffff8153dfa7>] kasan_report+0x167/0x360 mm/kasan/report.c:408
 [<ffffffff8153cac7>] check_memory_region_inline mm/kasan/kasan.c:318 [inline]
 [<ffffffff8153cac7>] check_memory_region+0x137/0x190 mm/kasan/kasan.c:325
 [<ffffffff8153cb31>] kasan_check_read+0x11/0x20 mm/kasan/kasan.c:330
 [<ffffffff82da5800>] copy_to_user arch/x86/include/asm/uaccess.h:716 [inline]
 [<ffffffff82da5800>] snd_timer_user_read+0x510/0x700 sound/core/timer.c:2006
 [<ffffffff8156c5c1>] do_loop_readv_writev.part.17+0x141/0x1e0 fs/read_write.c:714
 [<ffffffff81570430>] do_loop_readv_writev fs/read_write.c:880 [inline]
 [<ffffffff81570430>] do_readv_writev+0x520/0x750 fs/read_write.c:874
 [<ffffffff815706e4>] vfs_readv+0x84/0xc0 fs/read_write.c:898
 [<ffffffff81570806>] do_readv+0xe6/0x250 fs/read_write.c:924
 [<ffffffff81573cf7>] SYSC_readv fs/read_write.c:1011 [inline]
 [<ffffffff81573cf7>] SyS_readv+0x27/0x30 fs/read_write.c:1008
 [<ffffffff838b2c2e>] entry_SYSCALL_64_fastpath+0x29/0xe8
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..