================================================================== BUG: KASAN: use-after-free in mptcp_check_fallback net/mptcp/protocol.h:745 [inline] BUG: KASAN: use-after-free in mptcp_established_options+0x22cf/0x2780 net/mptcp/options.c:724 Read of size 8 at addr ffff888018812ca0 by task syz-executor.0/11915 CPU: 0 PID: 11915 Comm: syz-executor.0 Not tainted 5.11.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:230 __kasan_report mm/kasan/report.c:396 [inline] kasan_report.cold+0x79/0xd5 mm/kasan/report.c:413 mptcp_check_fallback net/mptcp/protocol.h:745 [inline] mptcp_established_options+0x22cf/0x2780 net/mptcp/options.c:724 tcp_established_options+0x4ed/0x700 net/ipv4/tcp_output.c:953 tcp_current_mss+0x1d2/0x360 net/ipv4/tcp_output.c:1840 tcp_send_mss+0x28/0x2b0 net/ipv4/tcp.c:943 mptcp_sendmsg_frag+0x13b/0x1220 net/mptcp/protocol.c:1266 mptcp_push_pending+0x2cc/0x650 net/mptcp/protocol.c:1477 mptcp_sendmsg+0xde4/0x2830 net/mptcp/protocol.c:1685 inet6_sendmsg+0x99/0xe0 net/ipv6/af_inet6.c:638 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 sock_write_iter+0x289/0x3c0 net/socket.c:999 call_write_iter include/linux/fs.h:1901 [inline] new_sync_write+0x426/0x650 fs/read_write.c:518 vfs_write+0x791/0xa30 fs/read_write.c:605 ksys_write+0x1ee/0x250 fs/read_write.c:658 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x465d99 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f05e1754188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000465d99 RDX: 0000000020000001 RSI: 0000000020000000 RDI: 0000000000000003 RBP: 00000000004bcf27 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008 R13: 00007fff0b24681f R14: 00007f05e1754300 R15: 0000000000022000 Allocated by task 11908: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:401 [inline] ____kasan_kmalloc.constprop.0+0x82/0xa0 mm/kasan/common.c:429 kmalloc include/linux/slab.h:552 [inline] kzalloc include/linux/slab.h:682 [inline] subflow_create_ctx+0x82/0x230 net/mptcp/subflow.c:1378 subflow_ulp_init+0x62/0x370 net/mptcp/subflow.c:1459 __tcp_set_ulp net/ipv4/tcp_ulp.c:139 [inline] tcp_set_ulp+0x27c/0x610 net/ipv4/tcp_ulp.c:160 mptcp_subflow_create_socket+0x5bf/0xe20 net/mptcp/subflow.c:1343 __mptcp_socket_create net/mptcp/protocol.c:110 [inline] mptcp_init_sock net/mptcp/protocol.c:2365 [inline] mptcp_init_sock+0x140/0x830 net/mptcp/protocol.c:2350 inet6_create net/ipv6/af_inet6.c:256 [inline] inet6_create+0xa15/0x1010 net/ipv6/af_inet6.c:110 __sock_create+0x3de/0x780 net/socket.c:1406 sock_create net/socket.c:1457 [inline] __sys_socket+0xef/0x200 net/socket.c:1499 __do_sys_socket net/socket.c:1508 [inline] __se_sys_socket net/socket.c:1506 [inline] __x64_sys_socket+0x6f/0xb0 net/socket.c:1506 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 7: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:356 ____kasan_slab_free+0xe1/0x110 mm/kasan/common.c:362 kasan_slab_free include/linux/kasan.h:192 [inline] slab_free_hook mm/slub.c:1547 [inline] slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1580 slab_free mm/slub.c:3143 [inline] kmem_cache_free_bulk mm/slub.c:3269 [inline] kmem_cache_free_bulk+0x253/0xc80 mm/slub.c:3256 kfree_bulk include/linux/slab.h:409 [inline] kfree_rcu_work+0x4cd/0x860 kernel/rcu/tree.c:3226 process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Last potentially related work creation: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_record_aux_stack+0xc5/0xf0 mm/kasan/generic.c:344 __call_rcu kernel/rcu/tree.c:2965 [inline] call_rcu+0xbb/0x700 kernel/rcu/tree.c:3038 free_fib_info net/ipv4/fib_semantics.c:256 [inline] fib_create_info+0x1fee/0x4870 net/ipv4/fib_semantics.c:1549 fib_table_insert+0x1cd/0x1af0 net/ipv4/fib_trie.c:1224 fib_magic+0x3b9/0x520 net/ipv4/fib_frontend.c:1085 fib_add_ifaddr+0x16c/0x520 net/ipv4/fib_frontend.c:1107 fib_netdev_event+0x488/0x670 net/ipv4/fib_frontend.c:1466 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2063 call_netdevice_notifiers_extack net/core/dev.c:2075 [inline] call_netdevice_notifiers net/core/dev.c:2089 [inline] __dev_notify_flags+0x110/0x2b0 net/core/dev.c:8699 dev_change_flags+0x112/0x170 net/core/dev.c:8737 do_setlink+0x89a/0x3a70 net/core/rtnetlink.c:2708 __rtnl_newlink+0xdc1/0x1700 net/core/rtnetlink.c:3376 rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3491 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5553 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2502 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 __sys_sendto+0x21c/0x320 net/socket.c:1975 __do_sys_sendto net/socket.c:1987 [inline] __se_sys_sendto net/socket.c:1983 [inline] __x64_sys_sendto+0xdd/0x1b0 net/socket.c:1983 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff888018812c00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 160 bytes inside of 256-byte region [ffff888018812c00, ffff888018812d00) The buggy address belongs to the page: page:00000000cea85763 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x18812 head:00000000cea85763 order:1 compound_mapcount:0 flags: 0xfff00000010200(slab|head) raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010c413c0 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888018812b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888018812c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888018812c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888018812d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888018812d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc 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