==================================================================
BUG: KASAN: null-ptr-deref in memcpy include/linux/string.h:344 [inline]
BUG: KASAN: null-ptr-deref in do_convert sound/core/oss/linear.c:52 [inline]
BUG: KASAN: null-ptr-deref in convert sound/core/oss/linear.c:81 [inline]
BUG: KASAN: null-ptr-deref in linear_transfer+0x634/0x900 sound/core/oss/linear.c:110
Write of size 2 at addr           (null) by task syz-executor4/3925

CPU: 1 PID: 3925 Comm: syz-executor4 Not tainted 4.15.0-rc6-mm1+ #52
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 kasan_report_error mm/kasan/report.c:352 [inline]
 kasan_report+0x13f/0x360 mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
 memcpy+0x37/0x50 mm/kasan/kasan.c:303
 memcpy include/linux/string.h:344 [inline]
 do_convert sound/core/oss/linear.c:52 [inline]
 convert sound/core/oss/linear.c:81 [inline]
 linear_transfer+0x634/0x900 sound/core/oss/linear.c:110
 snd_pcm_plug_write_transfer+0x24e/0x410 sound/core/oss/pcm_plugin.c:619
 snd_pcm_oss_write2+0x260/0x420 sound/core/oss/pcm_oss.c:1310
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1371 [inline]
 snd_pcm_oss_write+0x5fe/0x830 sound/core/oss/pcm_oss.c:2645
 do_loop_readv_writev fs/read_write.c:676 [inline]
 do_iter_write+0x3ca/0x540 fs/read_write.c:934
 vfs_writev+0x18a/0x340 fs/read_write.c:977
 do_writev+0xfc/0x2a0 fs/read_write.c:1012
 SYSC_writev fs/read_write.c:1085 [inline]
 SyS_writev+0x27/0x30 fs/read_write.c:1082
 entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x452ac9
RSP: 002b:00007fead96f7c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000071bf58 RCX: 0000000000452ac9
RDX: 0000000000000001 RSI: 000000002000c000 RDI: 0000000000000015
RBP: 0000000000000316 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f2ab0
R13: 00000000ffffffff R14: 00007fead96f86d4 R15: 0000000000000002
==================================================================
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 3925 Comm: syz-executor4 Tainted: G    B            4.15.0-rc6-mm1+ #52
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 panic+0x1e4/0x41c kernel/panic.c:183
 kasan_end_report+0x50/0x50 mm/kasan/report.c:180
 kasan_report_error mm/kasan/report.c:359 [inline]
 kasan_report+0x148/0x360 mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
 memcpy+0x37/0x50 mm/kasan/kasan.c:303
 memcpy include/linux/string.h:344 [inline]
 do_convert sound/core/oss/linear.c:52 [inline]
 convert sound/core/oss/linear.c:81 [inline]
 linear_transfer+0x634/0x900 sound/core/oss/linear.c:110
 snd_pcm_plug_write_transfer+0x24e/0x410 sound/core/oss/pcm_plugin.c:619
 snd_pcm_oss_write2+0x260/0x420 sound/core/oss/pcm_oss.c:1310
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1371 [inline]
 snd_pcm_oss_write+0x5fe/0x830 sound/core/oss/pcm_oss.c:2645
 do_loop_readv_writev fs/read_write.c:676 [inline]
 do_iter_write+0x3ca/0x540 fs/read_write.c:934
 vfs_writev+0x18a/0x340 fs/read_write.c:977
 do_writev+0xfc/0x2a0 fs/read_write.c:1012
 SYSC_writev fs/read_write.c:1085 [inline]
 SyS_writev+0x27/0x30 fs/read_write.c:1082
 entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x452ac9
RSP: 002b:00007fead96f7c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000071bf58 RCX: 0000000000452ac9
RDX: 0000000000000001 RSI: 000000002000c000 RDI: 0000000000000015
RBP: 0000000000000316 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f2ab0
R13: 00000000ffffffff R14: 00007fead96f86d4 R15: 0000000000000002
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..