==================================================================
BUG: KASAN: null-ptr-deref in copy_to_user arch/x86/include/asm/uaccess.h:731 [inline]
BUG: KASAN: null-ptr-deref in snd_timer_user_read+0x594/0x710 sound/core/timer.c:2006
Read of size 32 at addr           (null) by task syz-executor2/30057

CPU: 0 PID: 30057 Comm: syz-executor2 Not tainted 4.9.141+ #1
 ffff8801945ef968 ffffffff81b42e79 0000000000000000 0000000000000020
 0000000000000000 ffff8801945efb38 ffff8801c7563180 ffff8801945ef9b0
 ffffffff81500bed ffffffff8224e014 0000000000000286 e33b6880f418d4b9
Call Trace:
 [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81500bed>] kasan_report_error mm/kasan/report.c:353 [inline]
 [<ffffffff81500bed>] kasan_report.cold.6+0x6d/0x2fe mm/kasan/report.c:412
 [<ffffffff814f1dfd>] check_memory_region_inline mm/kasan/kasan.c:318 [inline]
 [<ffffffff814f1dfd>] check_memory_region+0x14d/0x1b0 mm/kasan/kasan.c:325
 [<ffffffff814f1e71>] kasan_check_read+0x11/0x20 mm/kasan/kasan.c:330
 [<ffffffff8224e014>] copy_to_user arch/x86/include/asm/uaccess.h:731 [inline]
 [<ffffffff8224e014>] snd_timer_user_read+0x594/0x710 sound/core/timer.c:2006
 [<ffffffff81509df5>] do_loop_readv_writev.part.1+0xd5/0x280 fs/read_write.c:718
 [<ffffffff8150b49e>] do_loop_readv_writev fs/read_write.c:707 [inline]
 [<ffffffff8150b49e>] do_readv_writev+0x56e/0x7b0 fs/read_write.c:873
 [<ffffffff8150b764>] vfs_readv+0x84/0xc0 fs/read_write.c:897
 [<ffffffff8150b886>] do_readv+0xe6/0x260 fs/read_write.c:923
 [<ffffffff8150f0e7>] SYSC_readv fs/read_write.c:1010 [inline]
 [<ffffffff8150f0e7>] SyS_readv+0x27/0x30 fs/read_write.c:1007
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
==================================================================
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 30057 Comm: syz-executor2 Tainted: G    B           4.9.141+ #1
 ffff8801945ef890 ffffffff81b42e79 ffffffff82e37630 00000000ffffffff
 0000000000000000 0000000000000000 ffff8801c7563180 ffff8801945ef950
 ffffffff813f7125 0000000041b58ab3 ffffffff82e2b62b ffffffff813f6f66
Call Trace:
 [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff813f7125>] panic+0x1bf/0x39f kernel/panic.c:179
 [<ffffffff815008d5>] kasan_end_report+0x47/0x4f mm/kasan/report.c:180
 [<ffffffff81500bf6>] kasan_report_error mm/kasan/report.c:360 [inline]
 [<ffffffff81500bf6>] kasan_report.cold.6+0x76/0x2fe mm/kasan/report.c:412
 [<ffffffff814f1dfd>] check_memory_region_inline mm/kasan/kasan.c:318 [inline]
 [<ffffffff814f1dfd>] check_memory_region+0x14d/0x1b0 mm/kasan/kasan.c:325
 [<ffffffff814f1e71>] kasan_check_read+0x11/0x20 mm/kasan/kasan.c:330
 [<ffffffff8224e014>] copy_to_user arch/x86/include/asm/uaccess.h:731 [inline]
 [<ffffffff8224e014>] snd_timer_user_read+0x594/0x710 sound/core/timer.c:2006
 [<ffffffff81509df5>] do_loop_readv_writev.part.1+0xd5/0x280 fs/read_write.c:718
 [<ffffffff8150b49e>] do_loop_readv_writev fs/read_write.c:707 [inline]
 [<ffffffff8150b49e>] do_readv_writev+0x56e/0x7b0 fs/read_write.c:873
 [<ffffffff8150b764>] vfs_readv+0x84/0xc0 fs/read_write.c:897
 [<ffffffff8150b886>] do_readv+0xe6/0x260 fs/read_write.c:923
 [<ffffffff8150f0e7>] SYSC_readv fs/read_write.c:1010 [inline]
 [<ffffffff8150f0e7>] SyS_readv+0x27/0x30 fs/read_write.c:1007
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Kernel Offset: disabled
Rebooting in 86400 seconds..