| From: Eric Dumazet <edumazet@google.com> |
| Date: Sat, 15 Jun 2019 16:28:48 -0700 |
| Subject: neigh: fix use-after-free read in pneigh_get_next |
| |
| commit f3e92cb8e2eb8c27d109e6fd73d3a69a8c09e288 upstream. |
| |
| Nine years ago, I added RCU handling to neighbours, not pneighbours. |
| (pneigh are not commonly used) |
| |
| Unfortunately I missed that /proc dump operations would use a |
| common entry and exit point : neigh_seq_start() and neigh_seq_stop() |
| |
| We need to read_lock(tbl->lock) or risk use-after-free while |
| iterating the pneigh structures. |
| |
| We might later convert pneigh to RCU and revert this patch. |
| |
| sysbot reported : |
| |
| BUG: KASAN: use-after-free in pneigh_get_next.isra.0+0x24b/0x280 net/core/neighbour.c:3158 |
| Read of size 8 at addr ffff888097f2a700 by task syz-executor.0/9825 |
| |
| CPU: 1 PID: 9825 Comm: syz-executor.0 Not tainted 5.2.0-rc4+ #32 |
| 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+0x172/0x1f0 lib/dump_stack.c:113 |
| print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188 |
| __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 |
| kasan_report+0x12/0x20 mm/kasan/common.c:614 |
| __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 |
| pneigh_get_next.isra.0+0x24b/0x280 net/core/neighbour.c:3158 |
| neigh_seq_next+0xdb/0x210 net/core/neighbour.c:3240 |
| seq_read+0x9cf/0x1110 fs/seq_file.c:258 |
| proc_reg_read+0x1fc/0x2c0 fs/proc/inode.c:221 |
| do_loop_readv_writev fs/read_write.c:714 [inline] |
| do_loop_readv_writev fs/read_write.c:701 [inline] |
| do_iter_read+0x4a4/0x660 fs/read_write.c:935 |
| vfs_readv+0xf0/0x160 fs/read_write.c:997 |
| kernel_readv fs/splice.c:359 [inline] |
| default_file_splice_read+0x475/0x890 fs/splice.c:414 |
| do_splice_to+0x127/0x180 fs/splice.c:877 |
| splice_direct_to_actor+0x2d2/0x970 fs/splice.c:954 |
| do_splice_direct+0x1da/0x2a0 fs/splice.c:1063 |
| do_sendfile+0x597/0xd00 fs/read_write.c:1464 |
| __do_sys_sendfile64 fs/read_write.c:1525 [inline] |
| __se_sys_sendfile64 fs/read_write.c:1511 [inline] |
| __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511 |
| do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 |
| entry_SYSCALL_64_after_hwframe+0x49/0xbe |
| RIP: 0033:0x4592c9 |
| Code: fd 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 |
| RSP: 002b:00007f4aab51dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 |
| RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000004592c9 |
| RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005 |
| RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 |
| R10: 0000000080000000 R11: 0000000000000246 R12: 00007f4aab51e6d4 |
| R13: 00000000004c689d R14: 00000000004db828 R15: 00000000ffffffff |
| |
| Allocated by task 9827: |
| save_stack+0x23/0x90 mm/kasan/common.c:71 |
| set_track mm/kasan/common.c:79 [inline] |
| __kasan_kmalloc mm/kasan/common.c:489 [inline] |
| __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462 |
| kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503 |
| __do_kmalloc mm/slab.c:3660 [inline] |
| __kmalloc+0x15c/0x740 mm/slab.c:3669 |
| kmalloc include/linux/slab.h:552 [inline] |
| pneigh_lookup+0x19c/0x4a0 net/core/neighbour.c:731 |
| arp_req_set_public net/ipv4/arp.c:1010 [inline] |
| arp_req_set+0x613/0x720 net/ipv4/arp.c:1026 |
| arp_ioctl+0x652/0x7f0 net/ipv4/arp.c:1226 |
| inet_ioctl+0x2a0/0x340 net/ipv4/af_inet.c:926 |
| sock_do_ioctl+0xd8/0x2f0 net/socket.c:1043 |
| sock_ioctl+0x3ed/0x780 net/socket.c:1194 |
| vfs_ioctl fs/ioctl.c:46 [inline] |
| file_ioctl fs/ioctl.c:509 [inline] |
| do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696 |
| ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 |
| __do_sys_ioctl fs/ioctl.c:720 [inline] |
| __se_sys_ioctl fs/ioctl.c:718 [inline] |
| __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 |
| do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 |
| entry_SYSCALL_64_after_hwframe+0x49/0xbe |
| |
| Freed by task 9824: |
| save_stack+0x23/0x90 mm/kasan/common.c:71 |
| set_track mm/kasan/common.c:79 [inline] |
| __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451 |
| kasan_slab_free+0xe/0x10 mm/kasan/common.c:459 |
| __cache_free mm/slab.c:3432 [inline] |
| kfree+0xcf/0x220 mm/slab.c:3755 |
| pneigh_ifdown_and_unlock net/core/neighbour.c:812 [inline] |
| __neigh_ifdown+0x236/0x2f0 net/core/neighbour.c:356 |
| neigh_ifdown+0x20/0x30 net/core/neighbour.c:372 |
| arp_ifdown+0x1d/0x21 net/ipv4/arp.c:1274 |
| inetdev_destroy net/ipv4/devinet.c:319 [inline] |
| inetdev_event+0xa14/0x11f0 net/ipv4/devinet.c:1544 |
| notifier_call_chain+0xc2/0x230 kernel/notifier.c:95 |
| __raw_notifier_call_chain kernel/notifier.c:396 [inline] |
| raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:403 |
| call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1749 |
| call_netdevice_notifiers_extack net/core/dev.c:1761 [inline] |
| call_netdevice_notifiers net/core/dev.c:1775 [inline] |
| rollback_registered_many+0x9b9/0xfc0 net/core/dev.c:8178 |
| rollback_registered+0x109/0x1d0 net/core/dev.c:8220 |
| unregister_netdevice_queue net/core/dev.c:9267 [inline] |
| unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9260 |
| unregister_netdevice include/linux/netdevice.h:2631 [inline] |
| __tun_detach+0xd8a/0x1040 drivers/net/tun.c:724 |
| tun_detach drivers/net/tun.c:741 [inline] |
| tun_chr_close+0xe0/0x180 drivers/net/tun.c:3451 |
| __fput+0x2ff/0x890 fs/file_table.c:280 |
| ____fput+0x16/0x20 fs/file_table.c:313 |
| task_work_run+0x145/0x1c0 kernel/task_work.c:113 |
| tracehook_notify_resume include/linux/tracehook.h:185 [inline] |
| exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168 |
| prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] |
| syscall_return_slowpath arch/x86/entry/common.c:279 [inline] |
| do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304 |
| entry_SYSCALL_64_after_hwframe+0x49/0xbe |
| |
| The buggy address belongs to the object at ffff888097f2a700 |
| which belongs to the cache kmalloc-64 of size 64 |
| The buggy address is located 0 bytes inside of |
| 64-byte region [ffff888097f2a700, ffff888097f2a740) |
| The buggy address belongs to the page: |
| page:ffffea00025fca80 refcount:1 mapcount:0 mapping:ffff8880aa400340 index:0x0 |
| flags: 0x1fffc0000000200(slab) |
| raw: 01fffc0000000200 ffffea000250d548 ffffea00025726c8 ffff8880aa400340 |
| raw: 0000000000000000 ffff888097f2a000 0000000100000020 0000000000000000 |
| page dumped because: kasan: bad access detected |
| |
| Memory state around the buggy address: |
| ffff888097f2a600: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc |
| ffff888097f2a680: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc |
| >ffff888097f2a700: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc |
| ^ |
| ffff888097f2a780: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc |
| ffff888097f2a800: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc |
| |
| Fixes: 767e97e1e0db ("neigh: RCU conversion of struct neighbour") |
| Signed-off-by: Eric Dumazet <edumazet@google.com> |
| Reported-by: syzbot <syzkaller@googlegroups.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| net/core/neighbour.c | 7 +++++++ |
| 1 file changed, 7 insertions(+) |
| |
| --- a/net/core/neighbour.c |
| +++ b/net/core/neighbour.c |
| @@ -2649,6 +2649,7 @@ static void *neigh_get_idx_any(struct se |
| } |
| |
| void *neigh_seq_start(struct seq_file *seq, loff_t *pos, struct neigh_table *tbl, unsigned int neigh_seq_flags) |
| + __acquires(tbl->lock) |
| __acquires(rcu_bh) |
| { |
| struct neigh_seq_state *state = seq->private; |
| @@ -2659,6 +2660,7 @@ void *neigh_seq_start(struct seq_file *s |
| |
| rcu_read_lock_bh(); |
| state->nht = rcu_dereference_bh(tbl->nht); |
| + read_lock(&tbl->lock); |
| |
| return *pos ? neigh_get_idx_any(seq, pos) : SEQ_START_TOKEN; |
| } |
| @@ -2692,8 +2694,13 @@ out: |
| EXPORT_SYMBOL(neigh_seq_next); |
| |
| void neigh_seq_stop(struct seq_file *seq, void *v) |
| + __releases(tbl->lock) |
| __releases(rcu_bh) |
| { |
| + struct neigh_seq_state *state = seq->private; |
| + struct neigh_table *tbl = state->tbl; |
| + |
| + read_unlock(&tbl->lock); |
| rcu_read_unlock_bh(); |
| } |
| EXPORT_SYMBOL(neigh_seq_stop); |