BUG: KASAN: use-after-free in tcp_skb_pcount include/net/tcp.h:911 [inline] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x1ae/0x200 net/ipv4/tcp_output.c:1790 Read of size 2 at addr ffff888099525570 by task syz-executor.4/7060 CPU: 1 PID: 7060 Comm: syz-executor.4 Not tainted 4.14.143 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x138/0x197 lib/dump_stack.c:53 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:428 tcp_skb_pcount include/net/tcp.h:911 [inline] tcp_init_tso_segs+0x1ae/0x200 net/ipv4/tcp_output.c:1790 tcp_write_xmit+0x15e/0x4960 net/ipv4/tcp_output.c:2330 __tcp_push_pending_frames+0xa6/0x260 net/ipv4/tcp_output.c:2563 tcp_send_fin+0x17e/0xc40 net/ipv4/tcp_output.c:3115 tcp_close+0xcc8/0xfb0 net/ipv4/tcp.c:2221 inet_release+0xec/0x1c0 net/ipv4/af_inet.c:425 __sock_release+0xce/0x2b0 net/socket.c:602 sock_close+0x1b/0x30 net/socket.c:1139 __fput+0x275/0x7a0 fs/file_table.c:210 ____fput+0x16/0x20 fs/file_table.c:244 task_work_run+0x114/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1da/0x220 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4bc/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4135d1 RSP: 002b:00007fff6b23cc80 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00000000004135d1 RDX: 0000001b33820000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000001 R08: 000000006e783fbb R09: 000000006e783fbf R10: 00007fff6b23cd60 R11: 0000000000000293 R12: 000000000075bf20 R13: 000000000002405c R14: 00000000007606e8 R15: ffffffffffffffff Allocated by task 7065: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x45/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc mm/kasan/kasan.c:551 [inline] kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc_node+0x144/0x780 mm/slab.c:3642 __alloc_skb+0x9c/0x500 net/core/skbuff.c:193 alloc_skb_fclone include/linux/skbuff.h:1022 [inline] sk_stream_alloc_skb+0xb3/0x780 net/ipv4/tcp.c:855 tcp_sendmsg_locked+0xf61/0x3200 net/ipv4/tcp.c:1301 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1457 inet_sendmsg+0x122/0x500 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xce/0x110 net/socket.c:656 sock_write_iter+0x21d/0x390 net/socket.c:925 call_write_iter include/linux/fs.h:1777 [inline] aio_write+0x2c7/0x4f0 fs/aio.c:1553 io_submit_one fs/aio.c:1641 [inline] do_io_submit+0x996/0x13f0 fs/aio.c:1709 SYSC_io_submit fs/aio.c:1734 [inline] SyS_io_submit+0x28/0x30 fs/aio.c:1731 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 7065: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x45/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kmem_cache_free+0x83/0x2b0 mm/slab.c:3758 kfree_skbmem+0x8d/0x120 net/core/skbuff.c:607 __kfree_skb+0x1e/0x30 net/core/skbuff.c:646 sk_wmem_free_skb include/net/sock.h:1416 [inline] tcp_remove_empty_skb.part.0+0x231/0x2e0 net/ipv4/tcp.c:929 tcp_remove_empty_skb net/ipv4/tcp.c:925 [inline] tcp_sendmsg_locked+0x1ced/0x3200 net/ipv4/tcp.c:1435 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1457 inet_sendmsg+0x122/0x500 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xce/0x110 net/socket.c:656 sock_write_iter+0x21d/0x390 net/socket.c:925 call_write_iter include/linux/fs.h:1777 [inline] aio_write+0x2c7/0x4f0 fs/aio.c:1553 io_submit_one fs/aio.c:1641 [inline] do_io_submit+0x996/0x13f0 fs/aio.c:1709 SYSC_io_submit fs/aio.c:1734 [inline] SyS_io_submit+0x28/0x30 fs/aio.c:1731 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 The buggy address belongs to the object at ffff888099525540 which belongs to the cache skbuff_fclone_cache of size 472 The buggy address is located 48 bytes inside of 472-byte region [ffff888099525540, ffff888099525718) The buggy address belongs to the page: page:ffffea0002654940 count:1 mapcount:0 mapping:ffff888099525040 index:0x0 flags: 0x1fffc0000000100(slab) raw: 01fffc0000000100 ffff888099525040 0000000000000000 0000000100000006 raw: ffffea00025cc8a0 ffffea00029860a0 ffff88821b7203c0 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888099525400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888099525480: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888099525500: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff888099525580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888099525600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== protocol 88fb is buggy, dev hsr_slave_0 protocol 88fb is buggy, dev hsr_slave_1 audit: type=1400 audit(1568487855.909:41): avc: denied { map } for pid=7053 comm="syz-executor.5" path="socket:[26217]" dev="sockfs" ino=26217 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=packet_socket permissive=1