Hello,

syzbot found the following crash on:

HEAD commit: faeacb6d net: tap: clean up an indentation issue git tree: net console output: https://syzkaller.appspot.com/x/log.txt?x=1241cbd3600000 kernel config: https://syzkaller.appspot.com/x/.config?x=6c210ff0b9a35071 dashboard link: https://syzkaller.appspot.com/bug?extid=0cc629f19ccb8534935b compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+0cc629f19ccb8534935b@syzkaller.appspotmail.com

================================================================== BUG: KASAN: use-after-free in memcpy include/linux/string.h:359 [inline] BUG: KASAN: use-after-free in batadv_iv_ogm_aggregate_new net/batman-adv/bat_iv_ogm.c:544 [inline] BUG: KASAN: use-after-free in batadv_iv_ogm_queue_add+0x31d/0x1120 net/batman-adv/bat_iv_ogm.c:640 Read of size 24 at addr ffff888099112740 by task kworker/u4:2/2025

CPU: 1 PID: 2025 Comm: kworker/u4:2 Not tainted 5.3.0+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482 kasan_report+0x12/0x17 mm/kasan/common.c:618 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x134/0x1a0 mm/kasan/generic.c:192 memcpy+0x24/0x50 mm/kasan/common.c:122 memcpy include/linux/string.h:359 [inline] batadv_iv_ogm_aggregate_new net/batman-adv/bat_iv_ogm.c:544 [inline] batadv_iv_ogm_queue_add+0x31d/0x1120 net/batman-adv/bat_iv_ogm.c:640 batadv_iv_ogm_schedule+0x783/0xe50 net/batman-adv/bat_iv_ogm.c:797 batadv_iv_send_outstanding_bat_ogm_packet+0x580/0x730 net/batman-adv/bat_iv_ogm.c:1675 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 9774: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_kmalloc mm/kasan/common.c:493 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:466 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:507 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3550 kmalloc include/linux/slab.h:552 [inline] batadv_iv_ogm_iface_enable+0x123/0x320 net/batman-adv/bat_iv_ogm.c:201 batadv_hardif_enable_interface+0x276/0x950 net/batman-adv/hard-interface.c:761 batadv_softif_slave_add+0x8f/0x100 net/batman-adv/soft-interface.c:892 do_set_master net/core/rtnetlink.c:2369 [inline] do_set_master+0x1ca/0x230 net/core/rtnetlink.c:2343 do_setlink+0xa85/0x3520 net/core/rtnetlink.c:2504 rtnl_setlink+0x273/0x3d0 net/core/rtnetlink.c:2763 rtnetlink_rcv_msg+0x463/0xb00 net/core/rtnetlink.c:5223 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477 rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5241 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline] netlink_unicast+0x531/0x710 net/netlink/af_netlink.c:1328 netlink_sendmsg+0x8a5/0xd60 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:637 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:657 sock_write_iter+0x27c/0x3e0 net/socket.c:989 call_write_iter include/linux/fs.h:1880 [inline] do_iter_readv_writev+0x5f8/0x8f0 fs/read_write.c:693 do_iter_write fs/read_write.c:970 [inline] do_iter_write+0x184/0x610 fs/read_write.c:951 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1015 do_writev+0x15b/0x330 fs/read_write.c:1058 __do_sys_writev fs/read_write.c:1131 [inline] __se_sys_writev fs/read_write.c:1128 [inline] __x64_sys_writev+0x75/0xb0 fs/read_write.c:1128 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 7: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:455 kasan_slab_free+0xe/0x10 mm/kasan/common.c:463 __cache_free mm/slab.c:3425 [inline] kfree+0x10a/0x2c0 mm/slab.c:3756 batadv_iv_ogm_iface_disable+0x39/0x80 net/batman-adv/bat_iv_ogm.c:220 batadv_hardif_disable_interface.cold+0x4b4/0x87b net/batman-adv/hard-interface.c:875 batadv_softif_destroy_netlink+0xa9/0x130 net/batman-adv/soft-interface.c:1146 default_device_exit_batch+0x25c/0x410 net/core/dev.c:9830 ops_exit_list.isra.0+0xfc/0x150 net/core/net_namespace.c:175 cleanup_net+0x4e2/0xa60 net/core/net_namespace.c:594 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff888099112740 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes inside of 32-byte region [ffff888099112740, ffff888099112760) The buggy address belongs to the page: page:ffffea0002644480 refcount:1 mapcount:0 mapping:ffff8880aa4001c0 index:0xffff888099112fc1 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea0002995848 ffffea00029e8bc8 ffff8880aa4001c0 raw: ffff888099112fc1 ffff888099112000 000000010000003a 0000000000000000 page dumped because: kasan: bad access detected

Memory state around the buggy address: ffff888099112600: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ffff888099112680: 00 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc

ffff888099112700: 00 00 00 fc fc fc fc fc fb fb fb fb fc fc fc fc

^ ffff888099112780: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ffff888099112800: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ==================================================================

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