================================================================== BUG: KASAN: use-after-free in crc16+0x1fc/0x280 lib/crc16.c:58 Read of size 1 at addr ffff8881a4959000 by task syz-executor.2/9176 CPU: 0 PID: 9176 Comm: syz-executor.2 Not tainted 5.4.225-syzkaller-00007-g250ac66f1853 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1d8/0x241 lib/dump_stack.c:118 print_address_description+0x8c/0x600 mm/kasan/report.c:384 __kasan_report+0xf3/0x120 mm/kasan/report.c:516 kasan_report+0x30/0x60 mm/kasan/common.c:653 crc16+0x1fc/0x280 lib/crc16.c:58 ext4_group_desc_csum+0x90b/0xc40 fs/ext4/super.c:2544 ext4_group_desc_csum_set+0x197/0x230 fs/ext4/super.c:2567 ext4_mb_mark_diskspace_used+0xa2d/0x1130 fs/ext4/mballoc.c:3035 ext4_mb_new_blocks+0x7d0/0x2d10 fs/ext4/mballoc.c:4594 ext4_ext_map_blocks+0x1e70/0x7450 fs/ext4/extents.c:4511 ext4_map_blocks+0xa83/0x1c40 fs/ext4/inode.c:659 _ext4_get_block+0x21b/0x610 fs/ext4/inode.c:810 ext4_block_write_begin+0x685/0x1180 fs/ext4/inode.c:1221 ext4_write_begin+0x5ba/0x1900 fs/ext4/inode.c:1359 ext4_da_write_begin+0x4a3/0xfe0 fs/ext4/inode.c:3117 generic_perform_write+0x2c7/0x560 mm/filemap.c:3311 __generic_file_write_iter+0x239/0x490 mm/filemap.c:3440 ext4_file_write_iter+0x499/0x10e0 fs/ext4/file.c:270 call_write_iter include/linux/fs.h:1981 [inline] new_sync_write fs/read_write.c:483 [inline] __vfs_write+0x5d3/0x750 fs/read_write.c:496 vfs_write+0x206/0x4e0 fs/read_write.c:558 ksys_write+0x199/0x2c0 fs/read_write.c:611 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Allocated by task 8732: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] __kasan_kmalloc+0x130/0x1d0 mm/kasan/common.c:529 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc_node mm/slub.c:2829 [inline] slab_alloc mm/slub.c:2837 [inline] kmem_cache_alloc+0xd0/0x220 mm/slub.c:2842 kmem_cache_zalloc include/linux/slab.h:680 [inline] __proc_create+0x419/0xa00 fs/proc/generic.c:424 _proc_mkdir+0xd3/0x200 fs/proc/generic.c:488 proc_net_mkdir include/linux/proc_fs.h:145 [inline] proc_net_ns_init+0x29f/0x3c0 fs/proc/proc_net.c:350 ops_init+0x1d7/0x4e0 net/core/net_namespace.c:138 setup_net+0x214/0x990 net/core/net_namespace.c:345 copy_net_ns+0x30f/0x510 net/core/net_namespace.c:486 create_new_namespaces+0x47a/0x570 kernel/nsproxy.c:103 copy_namespaces+0x169/0x1b0 kernel/nsproxy.c:161 copy_process+0x12da/0x3230 kernel/fork.c:2044 _do_fork+0x197/0x900 kernel/fork.c:2391 __do_sys_clone kernel/fork.c:2549 [inline] __se_sys_clone kernel/fork.c:2530 [inline] __x64_sys_clone+0x26b/0x2c0 kernel/fork.c:2530 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Freed by task 6932: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] kasan_set_free_info mm/kasan/common.c:345 [inline] __kasan_slab_free+0x178/0x230 mm/kasan/common.c:487 slab_free_hook mm/slub.c:1455 [inline] slab_free_freelist_hook mm/slub.c:1494 [inline] slab_free mm/slub.c:3080 [inline] kmem_cache_free+0xd5/0x290 mm/slub.c:3096 remove_proc_entry+0x411/0x530 fs/proc/generic.c:708 proc_net_ns_exit+0x43/0x60 fs/proc/proc_net.c:366 ops_exit_list net/core/net_namespace.c:179 [inline] cleanup_net+0x665/0xc90 net/core/net_namespace.c:609 process_one_work+0x765/0xd20 kernel/workqueue.c:2287 worker_thread+0xaef/0x1470 kernel/workqueue.c:2433 kthread+0x2da/0x360 kernel/kthread.c:288 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354 The buggy address belongs to the object at ffff8881a4959000 which belongs to the cache proc_dir_entry of size 192 The buggy address is located 0 bytes inside of 192-byte region [ffff8881a4959000, ffff8881a49590c0) The buggy address belongs to the page: page:ffffea0006925640 refcount:1 mapcount:0 mapping:ffff8881f5cfa280 index:0x0 flags: 0x8000000000000200(slab) raw: 8000000000000200 dead000000000100 dead000000000122 ffff8881f5cfa280 raw: 0000000000000000 0000000000100010 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) set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook mm/page_alloc.c:2165 [inline] prep_new_page+0x18f/0x370 mm/page_alloc.c:2171 get_page_from_freelist+0x2ce8/0x2d70 mm/page_alloc.c:3794 __alloc_pages_nodemask+0x393/0x840 mm/page_alloc.c:4891 alloc_slab_page+0x39/0x3c0 mm/slub.c:343 allocate_slab mm/slub.c:1683 [inline] new_slab+0x97/0x440 mm/slub.c:1749 new_slab_objects mm/slub.c:2505 [inline] ___slab_alloc+0x2fe/0x490 mm/slub.c:2667 __slab_alloc+0x5a/0x90 mm/slub.c:2707 slab_alloc_node mm/slub.c:2792 [inline] slab_alloc mm/slub.c:2837 [inline] kmem_cache_alloc+0x100/0x220 mm/slub.c:2842 kmem_cache_zalloc include/linux/slab.h:680 [inline] __proc_create+0x419/0xa00 fs/proc/generic.c:424 proc_create_reg fs/proc/generic.c:551 [inline] proc_create_single_data+0x123/0x240 fs/proc/generic.c:644 snmp6_register_dev+0xa1/0x110 net/ipv6/proc.c:254 ipv6_add_dev+0x51d/0x1070 net/ipv6/addrconf.c:408 addrconf_notify+0x59b/0xe50 net/ipv6/addrconf.c:3534 notifier_call_chain kernel/notifier.c:98 [inline] __raw_notifier_call_chain kernel/notifier.c:399 [inline] raw_notifier_call_chain+0x95/0x110 kernel/notifier.c:406 call_netdevice_notifiers_info net/core/dev.c:1670 [inline] call_netdevice_notifiers_extack net/core/dev.c:1682 [inline] call_netdevice_notifiers net/core/dev.c:1696 [inline] register_netdevice+0xeef/0x12a0 net/core/dev.c:9207 __ip_tunnel_create+0x2b0/0x370 net/ipv4/ip_tunnel.c:267 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1176 [inline] __free_pages_ok+0x83d/0x940 mm/page_alloc.c:1438 free_the_page mm/page_alloc.c:4953 [inline] __free_pages+0x91/0x140 mm/page_alloc.c:4959 __free_slab+0x221/0x2e0 mm/slub.c:1774 free_slab mm/slub.c:1789 [inline] discard_slab mm/slub.c:1795 [inline] unfreeze_partials+0x14e/0x180 mm/slub.c:2288 put_cpu_partial+0xb4/0x150 mm/slub.c:2324 __slab_free+0x288/0x350 mm/slub.c:2971 qlist_free_all+0x43/0xb0 mm/kasan/quarantine.c:167 quarantine_reduce+0x174/0x190 mm/kasan/quarantine.c:260 __kasan_kmalloc+0x43/0x1d0 mm/kasan/common.c:507 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc_node mm/slub.c:2829 [inline] slab_alloc mm/slub.c:2837 [inline] __kmalloc+0x100/0x2b0 mm/slub.c:3909 kmalloc include/linux/slab.h:561 [inline] kzalloc include/linux/slab.h:690 [inline] ops_init+0x85/0x4e0 net/core/net_namespace.c:128 setup_net+0x214/0x990 net/core/net_namespace.c:345 copy_net_ns+0x30f/0x510 net/core/net_namespace.c:486 create_new_namespaces+0x47a/0x570 kernel/nsproxy.c:103 copy_namespaces+0x169/0x1b0 kernel/nsproxy.c:161 copy_process+0x12da/0x3230 kernel/fork.c:2044 Memory state around the buggy address: ffff8881a4958f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8881a4958f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8881a4959000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881a4959080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff8881a4959100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================