==================================================================
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-executor4/7129

CPU: 0 PID: 7129 Comm: syz-executor4 Not tainted 4.9.141+ #23
 ffff8801c5e47958 ffffffff81b42e79 0000000000000000 0000000000000020
 0000000000000000 ffff8801c5e47b28 ffff8801ca32cf00 ffff8801c5e479a0
 ffffffff81500bed ffffffff8224e014 0000000000000282 aad78a5430ede23b
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
 [<ffffffff8150c710>] do_loop_readv_writev fs/read_write.c:707 [inline]
 [<ffffffff8150c710>] compat_do_readv_writev+0x570/0x7b0 fs/read_write.c:1091
 [<ffffffff8150ca32>] compat_readv+0xe2/0x150 fs/read_write.c:1120
 [<ffffffff8150cb92>] do_compat_readv+0xf2/0x1d0 fs/read_write.c:1140
 [<ffffffff8150f2c6>] C_SYSC_readv fs/read_write.c:1152 [inline]
 [<ffffffff8150f2c6>] compat_SyS_readv+0x26/0x30 fs/read_write.c:1148
 [<ffffffff81006311>] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
 [<ffffffff81006311>] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
 [<ffffffff82818de0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
==================================================================
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 7129 Comm: syz-executor4 Tainted: G    B           4.9.141+ #23
 ffff8801c5e47880 ffffffff81b42e79 ffffffff82e37630 00000000ffffffff
 0000000000000000 0000000000000000 ffff8801ca32cf00 ffff8801c5e47940
 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
 [<ffffffff8150c710>] do_loop_readv_writev fs/read_write.c:707 [inline]
 [<ffffffff8150c710>] compat_do_readv_writev+0x570/0x7b0 fs/read_write.c:1091
 [<ffffffff8150ca32>] compat_readv+0xe2/0x150 fs/read_write.c:1120
 [<ffffffff8150cb92>] do_compat_readv+0xf2/0x1d0 fs/read_write.c:1140
 [<ffffffff8150f2c6>] C_SYSC_readv fs/read_write.c:1152 [inline]
 [<ffffffff8150f2c6>] compat_SyS_readv+0x26/0x30 fs/read_write.c:1148
 [<ffffffff81006311>] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
 [<ffffffff81006311>] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
 [<ffffffff82818de0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
Kernel Offset: disabled
Rebooting in 86400 seconds..