From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: KASAN: use-after-free Read in fib6_table_lookup Date: Mon, 18 Jun 2018 05:14:48 -0700 Message-ID: <7cbcadba-a662-e26f-8523-9d5cabb05b3f@gmail.com> References: <00000000000031e74b056ee45c71@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit To: syzbot , davem@davemloft.net, kuznet@ms2.inr.ac.ru, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, David Ahern Return-path: In-Reply-To: <00000000000031e74b056ee45c71@google.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 06/17/2018 11:06 PM, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit:    f0dc7f9c6dd9 Merge git://git.kernel.org/pub/scm/linux/kern.. > git tree:       bpf-next > console output: https://syzkaller.appspot.com/x/log.txt?x=16725130400000 > kernel config:  https://syzkaller.appspot.com/x/.config?x=fa9c20c48788d1c1 > dashboard link: https://syzkaller.appspot.com/bug?extid=9e6d75e3edef427ee888 > compiler:       gcc (GCC) 8.0.1 20180413 (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+9e6d75e3edef427ee888@syzkaller.appspotmail.com > > ================================================================== > BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:188 [inline] > BUG: KASAN: use-after-free in find_rr_leaf net/ipv6/route.c:705 [inline] > BUG: KASAN: use-after-free in rt6_select net/ipv6/route.c:761 [inline] > BUG: KASAN: use-after-free in fib6_table_lookup+0x12b7/0x14d0 net/ipv6/route.c:1823 > Read of size 8 at addr ffff8801b5df2588 by task udevd/1407 > > overlayfs: unrecognized mount option "Sl�tI��p�5�Wӌ���c��&�e"�M��q�W����u�r'�v�-brE1n��U(��K�g�==;GZ�� ���<��2    N��𽸩��������l�8_��'�%]�]X�7���aNvD�cA��_�(�"��w��Q��++Q%5�����/��>*4Ϻ��k�{�)<��^rΎ�B��b̆��(�ӷ�ӌ���lå� > �b�� ������b�@iO�A�s��N�    � �91�¢��m�Gc����j��\�2G-k��'��UI�\8��}0��.�Gh�P�w�����U�^9�\���Sݐ�ʊ��n��a]��T�E�����gaj=Zڒ�_kP��l!�Þ���r��s��.�9��\�D]��b�y$���mQ�����ڨҙM�q��~vX'��6�ň$5��a+�.}�Uuc9݇o.׃�.S܉I��7�5�e�D8��k��E�M#������m�����Vy����7=jV����:�k[(>M > #�b���Z秺]k/^�����৴��;�v����`G6�m>���'e0��q > �s|�wJ�'rA����M�$���r0� u�UU~|��}>P{1flt��i�1+A�    �%۪(7˧Ȯ�?ܟ�����)_�����[�w������9W� > �،���&B�M�m�2�b֊ɹ�S@�q� > ��4j�h�%�� T�'$'�!�ٌt�4C3�g�nypBŔ���o�B�q �o�'􎪑�}��!�Tp9d˨���c��U`}_EҨ��\�I�X�—�q^�7-[��v[�-�_G�g)�?#~��h > CPU: 0 PID: 1407 Comm: udevd Not tainted 4.17.0+ #39 > 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+0x1b9/0x294 lib/dump_stack.c:113 >  print_address_description+0x6c/0x20b mm/kasan/report.c:256 >  kasan_report_error mm/kasan/report.c:354 [inline] >  kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 >  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 >  __read_once_size include/linux/compiler.h:188 [inline] >  find_rr_leaf net/ipv6/route.c:705 [inline] >  rt6_select net/ipv6/route.c:761 [inline] >  fib6_table_lookup+0x12b7/0x14d0 net/ipv6/route.c:1823 >  ip6_pol_route+0x1c2/0x1020 net/ipv6/route.c:1856 >  ip6_pol_route_output+0x54/0x70 net/ipv6/route.c:2082 >  fib6_rule_lookup+0x211/0x6d0 net/ipv6/fib6_rules.c:122 >  ip6_route_output_flags+0x2c5/0x350 net/ipv6/route.c:2110 >  ip6_route_output include/net/ip6_route.h:82 [inline] >  icmpv6_xrlim_allow net/ipv6/icmp.c:211 [inline] >  icmp6_send+0x147c/0x2da0 net/ipv6/icmp.c:535 >  icmpv6_send+0x17a/0x300 net/ipv6/ip6_icmp.c:43 >  ip6_link_failure+0xa5/0x790 net/ipv6/route.c:2244 >  dst_link_failure include/net/dst.h:427 [inline] >  ndisc_error_report+0xd1/0x1c0 net/ipv6/ndisc.c:695 >  neigh_invalidate+0x246/0x550 net/core/neighbour.c:892 >  neigh_timer_handler+0xaf9/0xde0 net/core/neighbour.c:978 >  call_timer_fn+0x230/0x940 kernel/time/timer.c:1326 >  expire_timers kernel/time/timer.c:1363 [inline] >  __run_timers+0x79e/0xc50 kernel/time/timer.c:1666 >  run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692 >  __do_softirq+0x2e0/0xaf5 kernel/softirq.c:284 >  invoke_softirq kernel/softirq.c:364 [inline] >  irq_exit+0x1d1/0x200 kernel/softirq.c:404 >  exiting_irq arch/x86/include/asm/apic.h:527 [inline] >  smp_apic_timer_interrupt+0x17e/0x710 arch/x86/kernel/apic/apic.c:1052 >  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863 >   > RIP: 0010:strlen+0x5e/0xa0 lib/string.c:482 > Code: 24 00 74 3b 48 bb 00 00 00 00 00 fc ff df 4c 89 e0 48 83 c0 01 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 0f b6 14 1a 38 ca 7f 04 <84> d2 75 23 80 38 00 75 de 48 83 c4 08 4c 29 e0 5b 41 5c 5d c3 48 > RSP: 0018:ffff8801af117850 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 > RAX: ffff880197f53bd0 RBX: dffffc0000000000 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: ffffffff81c5b06c RDI: ffff880197f53bc0 > RBP: ffff8801af117868 R08: ffff88019a976540 R09: 0000000000000000 > R10: ffff88019a976540 R11: 0000000000000000 R12: ffff880197f53bc0 > R13: ffff880197f53bc0 R14: ffffffff899e4e90 R15: ffff8801d91c6a00 >  strlen include/linux/string.h:267 [inline] >  getname_kernel+0x24/0x370 fs/namei.c:218 >  open_exec+0x17/0x70 fs/exec.c:882 >  load_elf_binary+0x968/0x5610 fs/binfmt_elf.c:780 >  search_binary_handler+0x17d/0x570 fs/exec.c:1653 >  exec_binprm fs/exec.c:1695 [inline] >  __do_execve_file.isra.35+0x16fe/0x2710 fs/exec.c:1819 >  do_execveat_common fs/exec.c:1866 [inline] >  do_execve fs/exec.c:1883 [inline] >  __do_sys_execve fs/exec.c:1964 [inline] >  __se_sys_execve fs/exec.c:1959 [inline] >  __x64_sys_execve+0x8f/0xc0 fs/exec.c:1959 >  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290 >  entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x7f1576a46207 > Code: 77 19 f4 48 89 d7 44 89 c0 0f 05 48 3d 00 f0 ff ff 76 e0 f7 d8 64 41 89 01 eb d8 f7 d8 64 41 89 01 eb df b8 3b 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 02 f3 c3 48 8b 15 00 8c 2d 00 f7 d8 64 89 02 > RSP: 002b:00007ffff2784568 EFLAGS: 00000202 ORIG_RAX: 000000000000003b > RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007f1576a46207 > RDX: 0000000001215b10 RSI: 00007ffff2784660 RDI: 00007ffff2785670 > RBP: 0000000000625500 R08: 000000000000589c R09: 000000000000589c > R10: 0000000000000000 R11: 0000000000000202 R12: 0000000001215b10 > R13: 0000000000000007 R14: 0000000001204250 R15: 0000000000000005 > > Allocated by task 12188: >  save_stack+0x43/0xd0 mm/kasan/kasan.c:448 >  set_track mm/kasan/kasan.c:460 [inline] >  kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 >  kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620 >  kmalloc include/linux/slab.h:513 [inline] >  kzalloc include/linux/slab.h:706 [inline] >  fib6_info_alloc+0xbb/0x280 net/ipv6/ip6_fib.c:152 >  ip6_route_info_create+0x782/0x2b50 net/ipv6/route.c:3013 >  ip6_route_add+0x23/0xb0 net/ipv6/route.c:3154 >  ipv6_route_ioctl+0x5a5/0x760 net/ipv6/route.c:3660 >  inet6_ioctl+0x100/0x1f0 net/ipv6/af_inet6.c:546 >  sock_do_ioctl+0xe4/0x3e0 net/socket.c:973 >  sock_ioctl+0x30d/0x680 net/socket.c:1097 >  vfs_ioctl fs/ioctl.c:46 [inline] >  file_ioctl fs/ioctl.c:500 [inline] >  do_vfs_ioctl+0x1cf/0x16f0 fs/ioctl.c:684 >  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701 >  __do_sys_ioctl fs/ioctl.c:708 [inline] >  __se_sys_ioctl fs/ioctl.c:706 [inline] >  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706 >  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290 >  entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Freed by task 1402: >  save_stack+0x43/0xd0 mm/kasan/kasan.c:448 >  set_track mm/kasan/kasan.c:460 [inline] >  __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 >  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 >  __cache_free mm/slab.c:3498 [inline] >  kfree+0xd9/0x260 mm/slab.c:3813 >  fib6_info_destroy+0x29b/0x350 net/ipv6/ip6_fib.c:207 >  fib6_info_release include/net/ip6_fib.h:286 [inline] >  __ip6_del_rt_siblings net/ipv6/route.c:3235 [inline] >  ip6_route_del+0x11c4/0x13b0 net/ipv6/route.c:3316 >  ipv6_route_ioctl+0x616/0x760 net/ipv6/route.c:3663 >  inet6_ioctl+0x100/0x1f0 net/ipv6/af_inet6.c:546 >  sock_do_ioctl+0xe4/0x3e0 net/socket.c:973 >  sock_ioctl+0x30d/0x680 net/socket.c:1097 >  vfs_ioctl fs/ioctl.c:46 [inline] >  file_ioctl fs/ioctl.c:500 [inline] >  do_vfs_ioctl+0x1cf/0x16f0 fs/ioctl.c:684 >  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701 >  __do_sys_ioctl fs/ioctl.c:708 [inline] >  __se_sys_ioctl fs/ioctl.c:706 [inline] >  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706 >  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290 >  entry_SYSCALL_64_after_hwframe+0x49/0xbe > > The buggy address belongs to the object at ffff8801b5df2580 >  which belongs to the cache kmalloc-256 of size 256 > The buggy address is located 8 bytes inside of >  256-byte region [ffff8801b5df2580, ffff8801b5df2680) > The buggy address belongs to the page: > page:ffffea0006d77c80 count:1 mapcount:0 mapping:ffff8801da8007c0 index:0xffff8801b5df2e40 > flags: 0x2fffc0000000100(slab) > raw: 02fffc0000000100 ffffea0006c5cc48 ffffea0007363308 ffff8801da8007c0 > raw: ffff8801b5df2e40 ffff8801b5df2080 0000000100000006 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: >  ffff8801b5df2480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >  ffff8801b5df2500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >> ffff8801b5df2580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >                       ^ >  ffff8801b5df2600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >  ffff8801b5df2680: fc fc fc fc fc fc fc fc 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@googlegroups.com. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot. I will test the following fix, and sent it formally. Fixes: a64efe142f5e ("net/ipv6: introduce fib6_info struct and helpers") diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h index 5cba71d2dc44b9ea2366725ff68c9f668f639345..71b9043aa0e7995c7e61f17b4493acd99410d1bc 100644 --- a/include/net/ip6_fib.h +++ b/include/net/ip6_fib.h @@ -170,6 +170,7 @@ struct fib6_info { unused:3; struct fib6_nh fib6_nh; + struct rcu_head rcu; }; struct rt6_info { @@ -273,7 +274,7 @@ static inline void ip6_rt_put(struct rt6_info *rt) } struct fib6_info *fib6_info_alloc(gfp_t gfp_flags); -void fib6_info_destroy(struct fib6_info *f6i); +void fib6_info_destroy_rcu(struct rcu_head *head); static inline void fib6_info_hold(struct fib6_info *f6i) { @@ -283,7 +284,7 @@ static inline void fib6_info_hold(struct fib6_info *f6i) static inline void fib6_info_release(struct fib6_info *f6i) { if (f6i && atomic_dec_and_test(&f6i->fib6_ref)) - fib6_info_destroy(f6i); + call_rcu(&f6i->rcu, fib6_info_destroy_rcu); } enum fib6_walk_state { diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 39d1d487eca25faceacbc3619fc6c4c38088d62a..1fb2f3118d60c73433e09f3a71abdbf9a8d92227 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -167,8 +167,9 @@ struct fib6_info *fib6_info_alloc(gfp_t gfp_flags) return f6i; } -void fib6_info_destroy(struct fib6_info *f6i) +void fib6_info_destroy_rcu(struct rcu_head *head) { + struct fib6_info *f6i = container_of(head, struct fib6_info, rcu); struct rt6_exception_bucket *bucket; struct dst_metrics *m; @@ -206,7 +207,7 @@ void fib6_info_destroy(struct fib6_info *f6i) kfree(f6i); } -EXPORT_SYMBOL_GPL(fib6_info_destroy); +EXPORT_SYMBOL_GPL(fib6_info_destroy_rcu); static struct fib6_node *node_alloc(struct net *net) {