Hello,

syzbot found the following crash on:

HEAD commit: 7c98a4261827 Merge tag 'ceph-for-4.20-rc4' of https://gith.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=142c8893400000 kernel config: https://syzkaller.appspot.com/x/.config?x=73e2bc0cb6463446 dashboard link: https://syzkaller.appspot.com/bug?extid=d4503ae45b65c5bc1194 compiler: gcc (GCC) 8.0.1 20180413 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1789354d400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=162ebe2b400000

IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+d4503ae45b65c5bc1194@syzkaller.appspotmail.com

RDX: 0000000056da83a0 RSI: 00000000200000c0 RDI: 0000000000000004 RBP: 00000000006cf018 R08: 0000000000000001 R09: 0000000000000037 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005 R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000 ================================================================== BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:352 [inline] BUG: KASAN: slab-out-of-bounds in default_write_copy_kernel+0xe1/0x140 sound/core/pcm_lib.c:1946 Read of size 64 at addr ffff8881cee03c40 by task syz-executor636/6021

CPU: 1 PID: 6021 Comm: syz-executor636 Not tainted 4.20.0-rc3+ #347 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x244/0x39d lib/dump_stack.c:113 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 memcpy+0x23/0x50 mm/kasan/kasan.c:302 memcpy include/linux/string.h:352 [inline] default_write_copy_kernel+0xe1/0x140 sound/core/pcm_lib.c:1946 interleaved_copy+0xd1/0x110 sound/core/pcm_lib.c:2007 __snd_pcm_lib_xfer+0x115f/0x1f23 sound/core/pcm_lib.c:2227 snd_pcm_oss_write3+0xe9/0x220 sound/core/oss/pcm_oss.c:1237 io_playback_transfer+0x27d/0x310 sound/core/oss/io.c:47 snd_pcm_plug_write_transfer+0x374/0x490 sound/core/oss/pcm_plugin.c:620 snd_pcm_oss_write2+0x25d/0x450 sound/core/oss/pcm_oss.c:1366 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1432 [inline] snd_pcm_oss_write+0x567/0xa60 sound/core/oss/pcm_oss.c:2775 __vfs_write+0x119/0x9f0 fs/read_write.c:485 vfs_write+0x1fc/0x560 fs/read_write.c:549 ksys_write+0x101/0x260 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x444119 Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffdf4510538 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000444119 RDX: 0000000056da83a0 RSI: 00000000200000c0 RDI: 0000000000000004 RBP: 00000000006cf018 R08: 0000000000000001 R09: 0000000000000037 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005 R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000

Allocated by task 6021: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 __do_kmalloc_node mm/slab.c:3684 [inline] __kmalloc_node+0x50/0x70 mm/slab.c:3691 kmalloc_node include/linux/slab.h:589 [inline] kvmalloc_node+0x65/0xf0 mm/util.c:416 kvmalloc include/linux/mm.h:577 [inline] kvzalloc include/linux/mm.h:585 [inline] snd_pcm_plugin_alloc+0x577/0x770 sound/core/oss/pcm_plugin.c:70 snd_pcm_plug_alloc+0x218/0x340 sound/core/oss/pcm_plugin.c:117 snd_pcm_oss_change_params_locked+0x2209/0x3c60 sound/core/oss/pcm_oss.c:1038 snd_pcm_oss_make_ready_locked+0xbc/0x130 sound/core/oss/pcm_oss.c:1183 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1397 [inline] snd_pcm_oss_write+0x51e/0xa60 sound/core/oss/pcm_oss.c:2775 __vfs_write+0x119/0x9f0 fs/read_write.c:485 vfs_write+0x1fc/0x560 fs/read_write.c:549 ksys_write+0x101/0x260 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 2446: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3817 blk_mq_hw_sysfs_release+0x42/0x60 block/blk-mq-sysfs.c:25 kobject_cleanup lib/kobject.c:662 [inline] kobject_release lib/kobject.c:691 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put.cold.9+0x287/0x2e4 lib/kobject.c:708 blk_mq_release+0xf2/0x210 block/blk-mq.c:2478 __blk_release_queue+0x228/0x510 block/blk-sysfs.c:862 process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296 kthread+0x35a/0x440 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8881cee03c40 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes inside of 32-byte region [ffff8881cee03c40, ffff8881cee03c60) The buggy address belongs to the page: page:ffffea00073b80c0 count:1 mapcount:0 mapping:ffff8881da8001c0 index:0xffff8881cee03fc1 flags: 0x2fffc0000000200(slab) raw: 02fffc0000000200 ffffea0007433308 ffff8881da801248 ffff8881da8001c0 raw: ffff8881cee03fc1 ffff8881cee03000 000000010000003f 0000000000000000 page dumped because: kasan: bad access detected

Memory state around the buggy address: ffff8881cee03b00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ffff8881cee03b80: fb fb fb fb fc fc fc fc 00 fc fc fc fc fc fc fc

ffff8881cee03c00: fb fb fb fb fc fc fc fc 00 00 00 00 fc fc fc fc

^ ffff8881cee03c80: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc ffff8881cee03d00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ==================================================================

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