bisecting fixing commit since b499cf4b3a901e87e1f933df04abf69b54de4457 building syzkaller on 35f5e45ed3cc032d9f969f3a8700e29607c1364f testing commit b499cf4b3a901e87e1f933df04abf69b54de4457 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 6df366d7a6380c27a141318d6c502588c585eeb9a6288b13fcdc4d010a6f6b49 run #0: crashed: KASAN: use-after-free Read in __lock_sock run #1: crashed: KASAN: use-after-free Read in __lock_sock run #2: crashed: KASAN: use-after-free Read in sctp_sock_dump run #3: crashed: KASAN: use-after-free Read in __lock_sock run #4: crashed: KASAN: use-after-free Read in __lock_sock run #5: crashed: KASAN: use-after-free Read in sctp_sock_dump run #6: crashed: KASAN: use-after-free Read in sctp_sock_dump run #7: crashed: KASAN: use-after-free Read in sctp_sock_dump run #8: crashed: KASAN: use-after-free Read in sctp_sock_dump run #9: crashed: KASAN: use-after-free Read in __lock_sock run #10: crashed: KASAN: use-after-free Read in __lock_sock run #11: crashed: KASAN: use-after-free Read in __lock_sock run #12: crashed: KASAN: use-after-free Read in __lock_sock run #13: crashed: KASAN: use-after-free Read in __lock_sock run #14: crashed: KASAN: use-after-free Read in __lock_sock run #15: crashed: KASAN: use-after-free Read in __lock_sock run #16: crashed: KASAN: use-after-free Read in __lock_sock run #17: crashed: KASAN: use-after-free Read in __lock_sock run #18: crashed: KASAN: use-after-free Read in __lock_sock run #19: crashed: KASAN: use-after-free Read in sctp_sock_dump testing current HEAD 2950c9c5e0df6bd34af45a5168bbee345e95eae2 testing commit 2950c9c5e0df6bd34af45a5168bbee345e95eae2 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 338b2800f087f279640d1557877855194ae35a59de54162f1e1e8e41ab43881f run #0: crashed: KASAN: use-after-free Read in sctp_sock_dump run #1: crashed: KASAN: use-after-free Read in lock_sock_nested run #2: crashed: KASAN: use-after-free Read in __lock_sock run #3: crashed: KASAN: use-after-free Read in __lock_sock run #4: crashed: KASAN: use-after-free Read in __lock_sock run #5: crashed: KASAN: use-after-free Read in sctp_sock_dump run #6: crashed: KASAN: use-after-free Read in __lock_sock run #7: crashed: KASAN: use-after-free Read in sctp_sock_dump run #8: crashed: KASAN: use-after-free Read in __lock_sock run #9: crashed: KASAN: use-after-free Read in __lock_sock revisions tested: 2, total time: 30m2.452407564s (build: 22m4.091295696s, test: 6m54.834730882s) the crash still happens on HEAD commit msg: Linux 4.19.207 crash: KASAN: use-after-free Read in __lock_sock IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready ================================================================== BUG: KASAN: use-after-free in __lock_acquire+0x33e0/0x4950 kernel/locking/lockdep.c:3295 Read of size 8 at addr ffff8881cee4f420 by task syz-executor.5/13132 CPU: 1 PID: 13132 Comm: syz-executor.5 Not tainted 4.19.207-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x171 lib/dump_stack.c:118 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report mm/kasan/report.c:412 [inline] kasan_report.cold.9+0x242/0x2fe mm/kasan/report.c:396 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 __lock_acquire+0x33e0/0x4950 kernel/locking/lockdep.c:3295 lock_acquire+0x173/0x3d0 kernel/locking/lockdep.c:3908 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168 spin_lock_bh include/linux/spinlock.h:334 [inline] __lock_sock+0x131/0x200 net/core/sock.c:2321 lock_sock_nested+0xda/0x100 net/core/sock.c:2866 lock_sock include/net/sock.h:1510 [inline] sctp_sock_dump+0x10b/0xc70 net/sctp/diag.c:321 sctp_for_each_transport+0x21e/0x280 net/sctp/socket.c:5081 sctp_diag_dump+0x271/0x510 net/sctp/diag.c:524 __inet_diag_dump+0x7f/0x110 net/ipv4/inet_diag.c:1058 inet_diag_dump+0x74/0xf0 net/ipv4/inet_diag.c:1074 netlink_dump+0x3aa/0xa80 net/netlink/af_netlink.c:2236 __netlink_dump_start+0x496/0x6c0 net/netlink/af_netlink.c:2332 netlink_dump_start include/linux/netlink.h:213 [inline] inet_diag_handler_cmd+0x1d5/0x2c0 net/ipv4/inet_diag.c:1179 __sock_diag_cmd net/core/sock_diag.c:232 [inline] sock_diag_rcv_msg+0x289/0x370 net/core/sock_diag.c:263 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2457 sock_diag_rcv+0x25/0x40 net/core/sock_diag.c:274 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x443/0x650 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x764/0xc60 net/netlink/af_netlink.c:1911 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xb5/0xf0 net/socket.c:661 sock_write_iter+0x215/0x420 net/socket.c:966 call_write_iter include/linux/fs.h:1821 [inline] do_iter_readv_writev+0x4ae/0x960 fs/read_write.c:681 do_iter_write fs/read_write.c:960 [inline] do_iter_write+0x12a/0x510 fs/read_write.c:941 vfs_writev+0x16f/0x2d0 fs/read_write.c:1005 do_writev+0x110/0x330 fs/read_write.c:1040 __do_sys_writev fs/read_write.c:1113 [inline] __se_sys_writev fs/read_write.c:1110 [inline] __x64_sys_writev+0x70/0xb0 fs/read_write.c:1110 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x462cd9 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:00007f97eb43c198 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 0000000000000cdd RCX: 0000000000462cd9 RDX: 0000000000000001 RSI: 0000000020000000 RDI: 000000000000000c RBP: 0000000000000014 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000052c050 R13: 00007f97eb43c6bc R14: 00000000ffffffff R15: 0000000000000003 Allocated by task 13126: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc mm/kasan/kasan.c:553 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:531 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x720 mm/slab.c:3559 sk_prot_alloc+0x5d/0x240 net/core/sock.c:1460 sk_alloc+0x30/0xca0 net/core/sock.c:1520 inet6_create net/ipv6/af_inet6.c:183 [inline] inet6_create+0x268/0xdd0 net/ipv6/af_inet6.c:110 __sock_create+0x262/0x540 net/socket.c:1365 sock_create net/socket.c:1416 [inline] __sys_socket+0xd7/0x1d0 net/socket.c:1458 __do_sys_socket net/socket.c:1467 [inline] __se_sys_socket net/socket.c:1465 [inline] __x64_sys_socket+0x6e/0xb0 net/socket.c:1465 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 13126: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kmem_cache_free+0x83/0x290 mm/slab.c:3765 sk_prot_free net/core/sock.c:1501 [inline] __sk_destruct+0x39d/0x600 net/core/sock.c:1584 sk_destruct+0x83/0xb0 net/core/sock.c:1599 __sk_free+0x9e/0x230 net/core/sock.c:1610 sk_free+0x1a/0x20 net/core/sock.c:1621 sock_put include/net/sock.h:1711 [inline] sctp_close+0x449/0x750 net/sctp/socket.c:1601 inet_release+0xb4/0x1b0 net/ipv4/af_inet.c:427 inet6_release+0x46/0x60 net/ipv6/af_inet6.c:472 __sock_release+0xc2/0x290 net/socket.c:599 sock_close+0x10/0x20 net/socket.c:1214 __fput+0x249/0x7f0 fs/file_table.c:278 ____fput+0x9/0x10 fs/file_table.c:309 task_work_run+0x108/0x180 kernel/task_work.c:113 get_signal+0x13a8/0x19e0 kernel/signal.c:2400 do_signal+0x87/0x1960 arch/x86/kernel/signal.c:799 exit_to_usermode_loop+0x114/0x200 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8881cee4f380 which belongs to the cache SCTPv6 of size 1928 The buggy address is located 160 bytes inside of 1928-byte region [ffff8881cee4f380, ffff8881cee4fb08) The buggy address belongs to the page: page:ffffea00073b9380 count:1 mapcount:0 mapping:ffff8881e4ea30c0 index:0x0 compound_mapcount: 0 flags: 0x17ffe0000008100(slab|head) raw: 017ffe0000008100 ffffea00073b9888 ffffea000777ba88 ffff8881e4ea30c0 raw: 0000000000000000 ffff8881cee4e300 0000000100000003 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881cee4f300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8881cee4f380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881cee4f400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881cee4f480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881cee4f500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================