On Wed, Jan 30, 2019 at 10:30 PM Paul Moore <paul@xxxxxxxxxxxxxx> wrote: > > On Wed, Jan 30, 2019 at 4:01 PM syzbot > <syzbot+1bfc00ca3aabe5bcd4cb@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: 62967898789d Merge git://git.kernel.org/pub/scm/linux/kern.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=167fdef8c00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=4fceea9e2d99ac20 > > dashboard link: https://syzkaller.appspot.com/bug?extid=1bfc00ca3aabe5bcd4cb > > 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+1bfc00ca3aabe5bcd4cb@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > 8021q: adding VLAN 0 to HW filter on device team0 > > ================================================================== > > BUG: KASAN: use-after-free in selinux_netlbl_socket_setsockopt+0x49b/0x510 > > security/selinux/netlabel.c:525 > > Read of size 8 at addr ffff8880a63cf078 by task syz-executor3/18477 > > > > CPU: 1 PID: 18477 Comm: syz-executor3 Not tainted 5.0.0-rc4+ #51 > > 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+0x1db/0x2d0 lib/dump_stack.c:113 > > print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 > > kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 > > __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135 > > selinux_netlbl_socket_setsockopt+0x49b/0x510 > > security/selinux/netlabel.c:525 > > At first glance this seems odd. The line above is simply > dereferencing sock->sk_security (getting the "sksec"), which we also > do higher up selinux_socket_setsockopt() via sock_has_perm(). Unless > somehow the socket is being released/freed in the middle of a > setsockopt() syscall this looks like maybe it's something else? Hi Paul, Searching for af_netrom across other syzbot bugs: https://groups.google.com/forum/#!searchin/syzkaller-bugs/af_netrom%7Csort:date I see at least: https://syzkaller.appspot.com/bug?extid=b0b1952f5864b4009b09 https://syzkaller.appspot.com/bug?extid=febf3c50d4262e578b1c https://syzkaller.appspot.com/bug?extid=defa700d16f1bd1b9a05 Which suggests there are some serious lifetime problems in netrom sockets. That would probably explain this crash as well. +netrom maintainers, does this explanation look plausible to you? should we dup this crash onto one of the other netrom bugs? and perhaps these netrom bugs across themselves too? > > selinux_socket_setsockopt+0x67/0x90 security/selinux/hooks.c:4693 > > security_socket_setsockopt+0x7d/0xc0 security/security.c:1467 > > __sys_setsockopt+0xe4/0x3a0 net/socket.c:1892 > > __do_sys_setsockopt net/socket.c:1913 [inline] > > __se_sys_setsockopt net/socket.c:1910 [inline] > > __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910 > > do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > RIP: 0033:0x458089 > > Code: 6d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > > RSP: 002b:00007fb988b9cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458089 > > RDX: 0000000000000078 RSI: 0000000000000084 RDI: 000000000000000a > > RBP: 000000000073c040 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb988b9d6d4 > > R13: 00000000004cc9e8 R14: 00000000004da6a8 R15: 00000000ffffffff > > > > Allocated by task 18471: > > save_stack+0x45/0xd0 mm/kasan/common.c:73 > > set_track mm/kasan/common.c:85 [inline] > > __kasan_kmalloc mm/kasan/common.c:496 [inline] > > __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:469 > > kasan_kmalloc+0x9/0x10 mm/kasan/common.c:504 > > __do_kmalloc mm/slab.c:3711 [inline] > > __kmalloc+0x15c/0x740 mm/slab.c:3720 > > kmalloc include/linux/slab.h:550 [inline] > > sk_prot_alloc+0x19c/0x2e0 net/core/sock.c:1477 > > sk_alloc+0xd7/0x1690 net/core/sock.c:1531 > > nr_create+0xb9/0x5e0 net/netrom/af_netrom.c:436 > > __sock_create+0x532/0x930 net/socket.c:1277 > > sock_create net/socket.c:1317 [inline] > > __sys_socket+0x106/0x260 net/socket.c:1347 > > __do_sys_socket net/socket.c:1356 [inline] > > __se_sys_socket net/socket.c:1354 [inline] > > __x64_sys_socket+0x73/0xb0 net/socket.c:1354 > > do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > Freed by task 18466: > > save_stack+0x45/0xd0 mm/kasan/common.c:73 > > set_track mm/kasan/common.c:85 [inline] > > __kasan_slab_free+0x102/0x150 mm/kasan/common.c:458 > > kasan_slab_free+0xe/0x10 mm/kasan/common.c:466 > > __cache_free mm/slab.c:3487 [inline] > > kfree+0xcf/0x230 mm/slab.c:3806 > > sk_prot_free net/core/sock.c:1514 [inline] > > __sk_destruct+0x76d/0xa60 net/core/sock.c:1596 > > sk_destruct+0x7b/0x90 net/core/sock.c:1604 > > __sk_free+0xce/0x300 net/core/sock.c:1615 > > sk_free+0x42/0x50 net/core/sock.c:1626 > > sock_put include/net/sock.h:1707 [inline] > > nr_release+0x337/0x3c0 net/netrom/af_netrom.c:557 > > __sock_release+0xd3/0x250 net/socket.c:579 > > sock_close+0x1b/0x30 net/socket.c:1141 > > __fput+0x3c5/0xb10 fs/file_table.c:278 > > ____fput+0x16/0x20 fs/file_table.c:309 > > task_work_run+0x1f4/0x2b0 kernel/task_work.c:113 > > tracehook_notify_resume include/linux/tracehook.h:188 [inline] > > exit_to_usermode_loop+0x32a/0x3b0 arch/x86/entry/common.c:166 > > prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] > > syscall_return_slowpath arch/x86/entry/common.c:268 [inline] > > do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > The buggy address belongs to the object at ffff8880a63cec80 > > which belongs to the cache kmalloc-2k of size 2048 > > The buggy address is located 1016 bytes inside of > > 2048-byte region [ffff8880a63cec80, ffff8880a63cf480) > > The buggy address belongs to the page: > > page:ffffea000298f380 count:1 mapcount:0 mapping:ffff88812c3f0c40 index:0x0 > > compound_mapcount: 0 > > flags: 0x1fffc0000010200(slab|head) > > raw: 01fffc0000010200 ffffea000127f888 ffffea00013a3188 ffff88812c3f0c40 > > raw: 0000000000000000 ffff8880a63ce400 0000000100000003 0000000000000000 > > page dumped because: kasan: bad access detected > > > > Memory state around the buggy address: > > ffff8880a63cef00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff8880a63cef80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > ffff8880a63cf000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ^ > > ffff8880a63cf080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff8880a63cf100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ================================================================== > > > > > > --- > > This bug is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > > > syzbot will keep track of this bug report. See: > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with > > syzbot. > > > > -- > paul moore > www.paul-moore.com
