Hello,

syzbot found the following issue on:

HEAD commit: 0a093b2893c7 Add linux-next specific files for 20230112 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=16d906ea480000 kernel config: https://syzkaller.appspot.com/x/.config?x=835f3591019836d5 dashboard link: https://syzkaller.appspot.com/bug?extid=ee73befabe68e7907adf compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/8111a570d6cb/disk-0a093b28.raw.... vmlinux: https://storage.googleapis.com/syzbot-assets/ecc135b7fc9a/vmlinux-0a093b28.x... kernel image: https://storage.googleapis.com/syzbot-assets/ca8d73b446ea/bzImage-0a093b28.x...

IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+ee73befabe68e7907adf@syzkaller.appspotmail.com

================================================================== BUG: KASAN: use-after-free in snd_pcm_oss_poll+0x91c/0xab0 sound/core/oss/pcm_oss.c:2849 Read of size 8 at addr ffff8880222ed980 by task syz-executor.0/13421

CPU: 0 PID: 13421 Comm: syz-executor.0 Not tainted 6.2.0-rc3-next-20230112-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:306 [inline] print_report+0x15e/0x45d mm/kasan/report.c:417 kasan_report+0xc0/0xf0 mm/kasan/report.c:517 snd_pcm_oss_poll+0x91c/0xab0 sound/core/oss/pcm_oss.c:2849 vfs_poll include/linux/poll.h:88 [inline] io_poll_check_events io_uring/poll.c:279 [inline] io_poll_task_func+0x3a6/0x1220 io_uring/poll.c:327 handle_tw_list+0xa8/0x460 io_uring/io_uring.c:1169 tctx_task_work+0x12e/0x530 io_uring/io_uring.c:1224 task_work_run+0x16f/0x270 kernel/task_work.c:179 get_signal+0x1c7/0x24f0 kernel/signal.c:2635 arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fbb08c8c0c9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fbb099a6218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 00007fbb08dabf88 RCX: 00007fbb08c8c0c9 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007fbb08dabf8c RBP: 00007fbb08dabf80 R08: 00007ffdf79a3080 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 00007fbb08dabf8c R13: 00007ffdf794d43f R14: 00007fbb099a6300 R15: 0000000000022000 </TASK>

Allocated by task 13421: kasan_save_stack+0x22/0x40 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:371 [inline] ____kasan_kmalloc mm/kasan/common.c:330 [inline] __kasan_kmalloc+0xa2/0xb0 mm/kasan/common.c:380 kmalloc include/linux/slab.h:580 [inline] kzalloc include/linux/slab.h:720 [inline] snd_pcm_oss_open_file sound/core/oss/pcm_oss.c:2433 [inline] snd_pcm_oss_open.part.0+0x558/0x1330 sound/core/oss/pcm_oss.c:2535 snd_pcm_oss_open+0x44/0x60 sound/core/oss/pcm_oss.c:2499 soundcore_open+0x452/0x620 sound/sound_core.c:593 chrdev_open+0x26a/0x770 fs/char_dev.c:414 do_dentry_open+0x6cc/0x13f0 fs/open.c:883 do_open fs/namei.c:3558 [inline] path_openat+0x1bc1/0x2b40 fs/namei.c:3715 do_filp_open+0x1ba/0x410 fs/namei.c:3742 do_sys_openat2+0x16d/0x4c0 fs/open.c:1311 do_sys_open fs/open.c:1327 [inline] __do_sys_openat fs/open.c:1343 [inline] __se_sys_openat fs/open.c:1338 [inline] __x64_sys_openat+0x143/0x1f0 fs/open.c:1338 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 13421: kasan_save_stack+0x22/0x40 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 kasan_save_free_info+0x2e/0x40 mm/kasan/generic.c:518 ____kasan_slab_free mm/kasan/common.c:236 [inline] ____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200 kasan_slab_free include/linux/kasan.h:162 [inline] slab_free_hook mm/slub.c:1781 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1807 slab_free mm/slub.c:3787 [inline] __kmem_cache_free+0xaf/0x2d0 mm/slub.c:3800 snd_pcm_oss_release_file sound/core/oss/pcm_oss.c:2415 [inline] snd_pcm_oss_release_file sound/core/oss/pcm_oss.c:2405 [inline] snd_pcm_oss_release+0x182/0x300 sound/core/oss/pcm_oss.c:2592 __fput+0x27c/0xa90 fs/file_table.c:321 task_work_run+0x16f/0x270 kernel/task_work.c:179 get_signal+0x1c7/0x24f0 kernel/signal.c:2635 arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff8880222ed980 which belongs to the cache kmalloc-16 of size 16 The buggy address is located 0 bytes inside of 16-byte region [ffff8880222ed980, ffff8880222ed990)

The buggy address belongs to the physical page: page:ffffea000088bb40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x222ed anon flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 ffff8880124413c0 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000800080 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 5107, tgid 5107 (syz-executor.1), ts 750843463810, free_ts 748166918947 prep_new_page mm/page_alloc.c:2549 [inline] get_page_from_freelist+0x11bb/0x2d50 mm/page_alloc.c:4324 __alloc_pages+0x1cb/0x5c0 mm/page_alloc.c:5590 __alloc_pages_node include/linux/gfp.h:237 [inline] alloc_slab_page mm/slub.c:1853 [inline] allocate_slab+0xa7/0x350 mm/slub.c:1998 new_slab mm/slub.c:2051 [inline] ___slab_alloc+0xa91/0x1400 mm/slub.c:3193 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3292 __slab_alloc_node mm/slub.c:3345 [inline] slab_alloc_node mm/slub.c:3442 [inline] __kmem_cache_alloc_node+0x136/0x330 mm/slub.c:3491 __do_kmalloc_node mm/slab_common.c:966 [inline] __kmalloc_node+0x4d/0xd0 mm/slab_common.c:974 kmalloc_node include/linux/slab.h:610 [inline] kvmalloc_node+0xa2/0x1a0 mm/util.c:603 xt_jumpstack_alloc net/netfilter/x_tables.c:1354 [inline] xt_replace_table+0x1a7/0x8c0 net/netfilter/x_tables.c:1393 __do_replace+0x1d7/0x8e0 net/ipv4/netfilter/ip_tables.c:1067 do_replace net/ipv4/netfilter/ip_tables.c:1140 [inline] do_ipt_set_ctl+0x89d/0xb10 net/ipv4/netfilter/ip_tables.c:1630 nf_setsockopt+0x87/0xe0 net/netfilter/nf_sockopt.c:101 ip_setsockopt+0xf2/0x110 net/ipv4/ip_sockglue.c:1445 tcp_setsockopt+0x9f/0x100 net/ipv4/tcp.c:3802 __sys_setsockopt+0x2c6/0x5b0 net/socket.c:2246 __do_sys_setsockopt net/socket.c:2257 [inline] __se_sys_setsockopt net/socket.c:2254 [inline] __x64_sys_setsockopt+0xbe/0x160 net/socket.c:2254 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1451 [inline] free_pcp_prepare+0x4d0/0x910 mm/page_alloc.c:1501 free_unref_page_prepare mm/page_alloc.c:3387 [inline] free_unref_page+0x1d/0x490 mm/page_alloc.c:3482 __unfreeze_partials+0x17c/0x1a0 mm/slub.c:2637 qlink_free mm/kasan/quarantine.c:168 [inline] qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187 kasan_quarantine_reduce+0x192/0x220 mm/kasan/quarantine.c:294 __kasan_slab_alloc+0x63/0x90 mm/kasan/common.c:302 kasan_slab_alloc include/linux/kasan.h:186 [inline] slab_post_alloc_hook mm/slab.h:769 [inline] slab_alloc_node mm/slub.c:3452 [inline] slab_alloc mm/slub.c:3460 [inline] __kmem_cache_alloc_lru mm/slub.c:3467 [inline] kmem_cache_alloc+0x175/0x320 mm/slub.c:3476 kmem_cache_zalloc include/linux/slab.h:710 [inline] alloc_buffer_head+0x24/0x150 fs/buffer.c:2946 alloc_page_buffers+0x284/0x790 fs/buffer.c:871 create_empty_buffers+0x30/0xf30 fs/buffer.c:1585 ext4_block_write_begin+0x10a7/0x15f0 fs/ext4/inode.c:1080 ext4_da_write_begin+0x450/0xb70 fs/ext4/inode.c:3082 generic_perform_write+0x256/0x570 mm/filemap.c:3772 ext4_buffered_write_iter+0x15b/0x460 fs/ext4/file.c:285 ext4_file_write_iter+0x8bf/0x1710 fs/ext4/file.c:700 __kernel_write_iter+0x262/0x730 fs/read_write.c:517

Memory state around the buggy address: ffff8880222ed880: 00 00 fc fc fa fb fc fc fa fb fc fc fa fb fc fc ffff8880222ed900: fa fb fc fc fa fb fc fc 00 00 fc fc 00 00 fc fc

ffff8880222ed980: fa fb fc fc fa fb fc fc 00 00 fc fc 00 00 fc fc

^ ffff8880222eda00: 00 00 fc fc 00 00 fc fc fa fb fc fc 00 00 fc fc ffff8880222eda80: fa fb fc fc 00 00 fc fc fa fb fc fc fa fb fc fc ==================================================================

--- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot.