On Tue, Jan 16, 2018 at 12:40 PM, syzbot <syzbot+8865eaff7f9acd593...@syzkaller.appspotmail.com> wrote: > syzkaller has found reproducer for the following crash on > a8750ddca918032d6349adbf9a4b6555e7db20da > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master > compiler: gcc (GCC) 7.1.1 20170620 > .config is attached > Raw console output is attached. > C reproducer is attached > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > for information about syzkaller reproducers > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+8865eaff7f9acd593...@syzkaller.appspotmail.com > It will help syzbot understand when the bug is fixed. > > ================================================================== > BUG: KASAN: use-after-free in psock_write_space+0x143/0x160 > net/kcm/kcmsock.c:418 > Read of size 8 at addr ffff8801bb731d20 by task syzkaller858097/3665 > > CPU: 0 PID: 3665 Comm: syzkaller858097 Not tainted 4.15.0-rc8+ #263 > 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+0x194/0x257 lib/dump_stack.c:53 > print_address_description+0x73/0x250 mm/kasan/report.c:252 > kasan_report_error mm/kasan/report.c:351 [inline] > kasan_report+0x25b/0x340 mm/kasan/report.c:409 > __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 > psock_write_space+0x143/0x160 net/kcm/kcmsock.c:418 > sock_wfree+0x10b/0x140 net/core/sock.c:1805 > skb_orphan include/linux/skbuff.h:2521 [inline] > loopback_xmit+0x12e/0x6b0 drivers/net/loopback.c:78 > __netdev_start_xmit include/linux/netdevice.h:4042 [inline] > netdev_start_xmit include/linux/netdevice.h:4051 [inline] > xmit_one net/core/dev.c:3003 [inline] > dev_hard_start_xmit+0x24e/0xac0 net/core/dev.c:3019 > __dev_queue_xmit+0x206d/0x2920 net/core/dev.c:3500 > dev_queue_xmit+0x17/0x20 net/core/dev.c:3533 > neigh_hh_output include/net/neighbour.h:472 [inline] > neigh_output include/net/neighbour.h:480 [inline] > ip6_finish_output2+0x1498/0x23a0 net/ipv6/ip6_output.c:120 > ip6_finish_output+0x302/0x930 net/ipv6/ip6_output.c:146 > NF_HOOK_COND include/linux/netfilter.h:239 [inline] > ip6_output+0x1eb/0x840 net/ipv6/ip6_output.c:163 > dst_output include/net/dst.h:460 [inline] > NF_HOOK include/linux/netfilter.h:250 [inline] > ip6_xmit+0xd84/0x2090 net/ipv6/ip6_output.c:269 > inet6_csk_xmit+0x2fc/0x580 net/ipv6/inet6_connection_sock.c:139 > dccp_transmit_skb+0x9ac/0x10f0 net/dccp/output.c:142 > dccp_send_reset+0x21c/0x2a0 net/dccp/output.c:530 > dccp_disconnect+0x90e/0xbb0 net/dccp/proto.c:276 > inet_child_forget+0x6b/0x320 net/ipv4/inet_connection_sock.c:899 > inet_csk_listen_stop+0x128/0x920 net/ipv4/inet_connection_sock.c:987 > dccp_close+0x780/0xc20 net/dccp/proto.c:1007 > inet_release+0xed/0x1c0 net/ipv4/af_inet.c:426 > inet6_release+0x50/0x70 net/ipv6/af_inet6.c:432 > sock_release+0x8d/0x1e0 net/socket.c:602 > sock_close+0x16/0x20 net/socket.c:1131 > __fput+0x327/0x7e0 fs/file_table.c:210 > ____fput+0x15/0x20 fs/file_table.c:244 > task_work_run+0x199/0x270 kernel/task_work.c:113 > exit_task_work include/linux/task_work.h:22 [inline] > do_exit+0x9bb/0x1ad0 kernel/exit.c:865 > do_group_exit+0x149/0x400 kernel/exit.c:968 > get_signal+0x73f/0x16c0 kernel/signal.c:2335 > do_signal+0x90/0x1eb0 arch/x86/kernel/signal.c:809 > exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158 > prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] > syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 > entry_SYSCALL_64_fastpath+0x9e/0xa0 > RIP: 0033:0x445819 > RSP: 002b:00007fad17780da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca > RAX: fffffffffffffe00 RBX: 00000000006dac3c RCX: 0000000000445819 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dac3c > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac38 > R13: 0100000000000000 R14: 656c6c616b7a7973 R15: 000000000000000b > > Allocated by task 3664: > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > set_track mm/kasan/kasan.c:459 [inline] > kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 > kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 > kmem_cache_alloc+0x12e/0x760 mm/slab.c:3544 > kmem_cache_zalloc include/linux/slab.h:678 [inline] > kcm_attach net/kcm/kcmsock.c:1394 [inline] > kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline] > kcm_ioctl+0x2d2/0x1690 net/kcm/kcmsock.c:1665 > sock_do_ioctl+0x65/0xb0 net/socket.c:966 > sock_ioctl+0x2c2/0x440 net/socket.c:1063 > vfs_ioctl fs/ioctl.c:46 [inline] > do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 > SYSC_ioctl fs/ioctl.c:701 [inline] > SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 > entry_SYSCALL_64_fastpath+0x29/0xa0 > > Freed by task 3665: > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > set_track mm/kasan/kasan.c:459 [inline] > kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 > __cache_free mm/slab.c:3488 [inline] > kmem_cache_free+0x83/0x2a0 mm/slab.c:3746 > kcm_unattach+0xe53/0x1510 net/kcm/kcmsock.c:1563 > release_mux net/kcm/kcmsock.c:1727 [inline] > kcm_done+0x5c7/0x1990 net/kcm/kcmsock.c:1787 > kcm_release+0x478/0x860 net/kcm/kcmsock.c:1861 > sock_release+0x8d/0x1e0 net/socket.c:602 > sock_close+0x16/0x20 net/socket.c:1131 > __fput+0x327/0x7e0 fs/file_table.c:210 > ____fput+0x15/0x20 fs/file_table.c:244 > task_work_run+0x199/0x270 kernel/task_work.c:113 > exit_task_work include/linux/task_work.h:22 [inline] > do_exit+0x9bb/0x1ad0 kernel/exit.c:865 > do_group_exit+0x149/0x400 kernel/exit.c:968 > get_signal+0x73f/0x16c0 kernel/signal.c:2335 > do_signal+0x90/0x1eb0 arch/x86/kernel/signal.c:809 > exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158 > prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] > syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 > entry_SYSCALL_64_fastpath+0x9e/0xa0 > > The buggy address belongs to the object at ffff8801bb731bc0 > which belongs to the cache kcm_psock_cache of size 544 > The buggy address is located 352 bytes inside of > 544-byte region [ffff8801bb731bc0, ffff8801bb731de0) > The buggy address belongs to the page: > page:ffffea0006edcc00 count:1 mapcount:0 mapping:ffff8801bb730040 index:0x0 > compound_mapcount: 0 > flags: 0x2fffc0000008100(slab|head) > raw: 02fffc0000008100 ffff8801bb730040 0000000000000000 000000010000000b > raw: ffff8801d3271348 ffff8801d3271348 ffff8801d3255780 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801bb731c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801bb731c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> >> ffff8801bb731d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ^ > ffff8801bb731d80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > ffff8801bb731e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ================================================================== >
I believe we need to free psock in RCU. I'll create a patch.