loop4: detected capacity change from 0 to 128 VFS: Found a Xenix FS (block size = 1024) on device loop4 ================================================================== BUG: KASAN: use-after-free in sysv_new_block+0x5d0/0x768 fs/sysv/balloc.c:113 Read of size 4 at addr ffff0000f3db90c8 by task syz.4.61/4703 CPU: 0 PID: 4703 Comm: syz.4.61 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106 print_address_description+0x88/0x218 mm/kasan/report.c:316 print_report+0x50/0x68 mm/kasan/report.c:420 kasan_report+0xa8/0x100 mm/kasan/report.c:524 __asan_report_load4_noabort+0x2c/0x38 mm/kasan/report_generic.c:350 sysv_new_block+0x5d0/0x768 fs/sysv/balloc.c:113 alloc_branch fs/sysv/itree.c:134 [inline] get_block+0x204/0x1210 fs/sysv/itree.c:253 __block_write_begin_int+0x34c/0x13b8 fs/buffer.c:1991 __block_write_begin fs/buffer.c:2041 [inline] block_write_begin+0x98/0x11c fs/buffer.c:2102 sysv_write_begin+0x44/0x88 fs/sysv/itree.c:487 generic_perform_write+0x230/0x4e4 mm/filemap.c:3862 __generic_file_write_iter+0x130/0x250 mm/filemap.c:3960 generic_file_write_iter+0xb4/0x2b0 mm/filemap.c:3989 call_write_iter include/linux/fs.h:2265 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x5ac/0x7c4 fs/read_write.c:584 ksys_write+0x120/0x210 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:646 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Allocated by task 4641: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:52 kasan_save_alloc_info+0x28/0x34 mm/kasan/generic.c:505 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slab_common.c:936 [inline] __kmalloc_node_track_caller+0xe0/0x16c mm/slab_common.c:956 kmalloc_reserve net/core/skbuff.c:446 [inline] __alloc_skb+0x264/0x718 net/core/skbuff.c:515 alloc_skb include/linux/skbuff.h:1271 [inline] nlmsg_new include/net/netlink.h:991 [inline] inet_netconf_notify_devconf+0x194/0x25c net/ipv4/devinet.c:2128 __devinet_sysctl_register+0x280/0x2f0 net/ipv4/devinet.c:2618 devinet_sysctl_register+0x14c/0x1c0 net/ipv4/devinet.c:2652 inetdev_init+0x268/0x4a8 net/ipv4/devinet.c:280 inetdev_event+0xf0c/0x12ec net/ipv4/devinet.c:1547 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:455 call_netdevice_notifiers_info net/core/dev.c:2001 [inline] call_netdevice_notifiers_extack net/core/dev.c:2039 [inline] call_netdevice_notifiers+0x10c/0x18c net/core/dev.c:2053 register_netdevice+0x1188/0x15cc net/core/dev.c:10237 veth_newlink+0x62c/0xa24 drivers/net/veth.c:1756 rtnl_newlink_create net/core/rtnetlink.c:3422 [inline] __rtnl_newlink net/core/rtnetlink.c:3642 [inline] rtnl_newlink+0x102c/0x1a1c net/core/rtnetlink.c:3655 rtnetlink_rcv_msg+0x734/0xce4 net/core/rtnetlink.c:6150 netlink_rcv_skb+0x208/0x3c4 net/netlink/af_netlink.c:2511 rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6168 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x60c/0x824 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x6e8/0x9b0 net/netlink/af_netlink.c:1872 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] __sys_sendto+0x304/0x3fc net/socket.c:2153 __do_sys_sendto net/socket.c:2165 [inline] __se_sys_sendto net/socket.c:2161 [inline] __arm64_sys_sendto+0xd8/0xf8 net/socket.c:2161 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Freed by task 4641: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:52 kasan_save_free_info+0x3c/0x60 mm/kasan/generic.c:516 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:236 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:244 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1729 [inline] slab_free_freelist_hook+0x16c/0x1ec mm/slub.c:1755 slab_free mm/slub.c:3687 [inline] __kmem_cache_free+0xc0/0x224 mm/slub.c:3700 kfree+0xd0/0x1ac mm/slab_common.c:988 skb_free_head net/core/skbuff.c:762 [inline] skb_release_data+0x43c/0x648 net/core/skbuff.c:791 skb_release_all net/core/skbuff.c:856 [inline] __kfree_skb net/core/skbuff.c:870 [inline] consume_skb+0xa0/0x104 net/core/skbuff.c:1035 netlink_broadcast+0xf30/0x108c net/netlink/af_netlink.c:1521 nlmsg_multicast include/net/netlink.h:1071 [inline] nlmsg_notify+0xf4/0x1d8 net/netlink/af_netlink.c:2554 rtnl_notify+0xa0/0xd8 net/core/rtnetlink.c:796 inet_netconf_notify_devconf+0x1f0/0x25c net/ipv4/devinet.c:2140 __devinet_sysctl_register+0x280/0x2f0 net/ipv4/devinet.c:2618 devinet_sysctl_register+0x14c/0x1c0 net/ipv4/devinet.c:2652 inetdev_init+0x268/0x4a8 net/ipv4/devinet.c:280 inetdev_event+0xf0c/0x12ec net/ipv4/devinet.c:1547 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:455 call_netdevice_notifiers_info net/core/dev.c:2001 [inline] call_netdevice_notifiers_extack net/core/dev.c:2039 [inline] call_netdevice_notifiers+0x10c/0x18c net/core/dev.c:2053 register_netdevice+0x1188/0x15cc net/core/dev.c:10237 veth_newlink+0x62c/0xa24 drivers/net/veth.c:1756 rtnl_newlink_create net/core/rtnetlink.c:3422 [inline] __rtnl_newlink net/core/rtnetlink.c:3642 [inline] rtnl_newlink+0x102c/0x1a1c net/core/rtnetlink.c:3655 rtnetlink_rcv_msg+0x734/0xce4 net/core/rtnetlink.c:6150 netlink_rcv_skb+0x208/0x3c4 net/netlink/af_netlink.c:2511 rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6168 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x60c/0x824 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x6e8/0x9b0 net/netlink/af_netlink.c:1872 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] __sys_sendto+0x304/0x3fc net/socket.c:2153 __do_sys_sendto net/socket.c:2165 [inline] __se_sys_sendto net/socket.c:2161 [inline] __arm64_sys_sendto+0xd8/0xf8 net/socket.c:2161 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 The buggy address belongs to the object at ffff0000f3db9000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 200 bytes inside of 512-byte region [ffff0000f3db9000, ffff0000f3db9200) The buggy address belongs to the physical page: page:000000009c5cde56 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x133db8 head:000000009c5cde56 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000010200 0000000000000000 dead000000000001 ffff0000c0002600 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000f3db8f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000f3db9000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff0000f3db9080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000f3db9100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000f3db9180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================