| From foo@baz Wed May 31 09:13:34 JST 2017 |
| From: Craig Gallek <kraig@google.com> |
| Date: Tue, 16 May 2017 14:36:23 -0400 |
| Subject: ipv6: Prevent overrun when parsing v6 header options |
| |
| From: Craig Gallek <kraig@google.com> |
| |
| |
| [ Upstream commit 2423496af35d94a87156b063ea5cedffc10a70a1 ] |
| |
| The KASAN warning repoted below was discovered with a syzkaller |
| program. The reproducer is basically: |
| int s = socket(AF_INET6, SOCK_RAW, NEXTHDR_HOP); |
| send(s, &one_byte_of_data, 1, MSG_MORE); |
| send(s, &more_than_mtu_bytes_data, 2000, 0); |
| |
| The socket() call sets the nexthdr field of the v6 header to |
| NEXTHDR_HOP, the first send call primes the payload with a non zero |
| byte of data, and the second send call triggers the fragmentation path. |
| |
| The fragmentation code tries to parse the header options in order |
| to figure out where to insert the fragment option. Since nexthdr points |
| to an invalid option, the calculation of the size of the network header |
| can made to be much larger than the linear section of the skb and data |
| is read outside of it. |
| |
| This fix makes ip6_find_1stfrag return an error if it detects |
| running out-of-bounds. |
| |
| [ 42.361487] ================================================================== |
| [ 42.364412] BUG: KASAN: slab-out-of-bounds in ip6_fragment+0x11c8/0x3730 |
| [ 42.365471] Read of size 840 at addr ffff88000969e798 by task ip6_fragment-oo/3789 |
| [ 42.366469] |
| [ 42.366696] CPU: 1 PID: 3789 Comm: ip6_fragment-oo Not tainted 4.11.0+ #41 |
| [ 42.367628] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1ubuntu1 04/01/2014 |
| [ 42.368824] Call Trace: |
| [ 42.369183] dump_stack+0xb3/0x10b |
| [ 42.369664] print_address_description+0x73/0x290 |
| [ 42.370325] kasan_report+0x252/0x370 |
| [ 42.370839] ? ip6_fragment+0x11c8/0x3730 |
| [ 42.371396] check_memory_region+0x13c/0x1a0 |
| [ 42.371978] memcpy+0x23/0x50 |
| [ 42.372395] ip6_fragment+0x11c8/0x3730 |
| [ 42.372920] ? nf_ct_expect_unregister_notifier+0x110/0x110 |
| [ 42.373681] ? ip6_copy_metadata+0x7f0/0x7f0 |
| [ 42.374263] ? ip6_forward+0x2e30/0x2e30 |
| [ 42.374803] ip6_finish_output+0x584/0x990 |
| [ 42.375350] ip6_output+0x1b7/0x690 |
| [ 42.375836] ? ip6_finish_output+0x990/0x990 |
| [ 42.376411] ? ip6_fragment+0x3730/0x3730 |
| [ 42.376968] ip6_local_out+0x95/0x160 |
| [ 42.377471] ip6_send_skb+0xa1/0x330 |
| [ 42.377969] ip6_push_pending_frames+0xb3/0xe0 |
| [ 42.378589] rawv6_sendmsg+0x2051/0x2db0 |
| [ 42.379129] ? rawv6_bind+0x8b0/0x8b0 |
| [ 42.379633] ? _copy_from_user+0x84/0xe0 |
| [ 42.380193] ? debug_check_no_locks_freed+0x290/0x290 |
| [ 42.380878] ? ___sys_sendmsg+0x162/0x930 |
| [ 42.381427] ? rcu_read_lock_sched_held+0xa3/0x120 |
| [ 42.382074] ? sock_has_perm+0x1f6/0x290 |
| [ 42.382614] ? ___sys_sendmsg+0x167/0x930 |
| [ 42.383173] ? lock_downgrade+0x660/0x660 |
| [ 42.383727] inet_sendmsg+0x123/0x500 |
| [ 42.384226] ? inet_sendmsg+0x123/0x500 |
| [ 42.384748] ? inet_recvmsg+0x540/0x540 |
| [ 42.385263] sock_sendmsg+0xca/0x110 |
| [ 42.385758] SYSC_sendto+0x217/0x380 |
| [ 42.386249] ? SYSC_connect+0x310/0x310 |
| [ 42.386783] ? __might_fault+0x110/0x1d0 |
| [ 42.387324] ? lock_downgrade+0x660/0x660 |
| [ 42.387880] ? __fget_light+0xa1/0x1f0 |
| [ 42.388403] ? __fdget+0x18/0x20 |
| [ 42.388851] ? sock_common_setsockopt+0x95/0xd0 |
| [ 42.389472] ? SyS_setsockopt+0x17f/0x260 |
| [ 42.390021] ? entry_SYSCALL_64_fastpath+0x5/0xbe |
| [ 42.390650] SyS_sendto+0x40/0x50 |
| [ 42.391103] entry_SYSCALL_64_fastpath+0x1f/0xbe |
| [ 42.391731] RIP: 0033:0x7fbbb711e383 |
| [ 42.392217] RSP: 002b:00007ffff4d34f28 EFLAGS: 00000246 ORIG_RAX: 000000000000002c |
| [ 42.393235] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbbb711e383 |
| [ 42.394195] RDX: 0000000000001000 RSI: 00007ffff4d34f60 RDI: 0000000000000003 |
| [ 42.395145] RBP: 0000000000000046 R08: 00007ffff4d34f40 R09: 0000000000000018 |
| [ 42.396056] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400aad |
| [ 42.396598] R13: 0000000000000066 R14: 00007ffff4d34ee0 R15: 00007fbbb717af00 |
| [ 42.397257] |
| [ 42.397411] Allocated by task 3789: |
| [ 42.397702] save_stack_trace+0x16/0x20 |
| [ 42.398005] save_stack+0x46/0xd0 |
| [ 42.398267] kasan_kmalloc+0xad/0xe0 |
| [ 42.398548] kasan_slab_alloc+0x12/0x20 |
| [ 42.398848] __kmalloc_node_track_caller+0xcb/0x380 |
| [ 42.399224] __kmalloc_reserve.isra.32+0x41/0xe0 |
| [ 42.399654] __alloc_skb+0xf8/0x580 |
| [ 42.400003] sock_wmalloc+0xab/0xf0 |
| [ 42.400346] __ip6_append_data.isra.41+0x2472/0x33d0 |
| [ 42.400813] ip6_append_data+0x1a8/0x2f0 |
| [ 42.401122] rawv6_sendmsg+0x11ee/0x2db0 |
| [ 42.401505] inet_sendmsg+0x123/0x500 |
| [ 42.401860] sock_sendmsg+0xca/0x110 |
| [ 42.402209] ___sys_sendmsg+0x7cb/0x930 |
| [ 42.402582] __sys_sendmsg+0xd9/0x190 |
| [ 42.402941] SyS_sendmsg+0x2d/0x50 |
| [ 42.403273] entry_SYSCALL_64_fastpath+0x1f/0xbe |
| [ 42.403718] |
| [ 42.403871] Freed by task 1794: |
| [ 42.404146] save_stack_trace+0x16/0x20 |
| [ 42.404515] save_stack+0x46/0xd0 |
| [ 42.404827] kasan_slab_free+0x72/0xc0 |
| [ 42.405167] kfree+0xe8/0x2b0 |
| [ 42.405462] skb_free_head+0x74/0xb0 |
| [ 42.405806] skb_release_data+0x30e/0x3a0 |
| [ 42.406198] skb_release_all+0x4a/0x60 |
| [ 42.406563] consume_skb+0x113/0x2e0 |
| [ 42.406910] skb_free_datagram+0x1a/0xe0 |
| [ 42.407288] netlink_recvmsg+0x60d/0xe40 |
| [ 42.407667] sock_recvmsg+0xd7/0x110 |
| [ 42.408022] ___sys_recvmsg+0x25c/0x580 |
| [ 42.408395] __sys_recvmsg+0xd6/0x190 |
| [ 42.408753] SyS_recvmsg+0x2d/0x50 |
| [ 42.409086] entry_SYSCALL_64_fastpath+0x1f/0xbe |
| [ 42.409513] |
| [ 42.409665] The buggy address belongs to the object at ffff88000969e780 |
| [ 42.409665] which belongs to the cache kmalloc-512 of size 512 |
| [ 42.410846] The buggy address is located 24 bytes inside of |
| [ 42.410846] 512-byte region [ffff88000969e780, ffff88000969e980) |
| [ 42.411941] The buggy address belongs to the page: |
| [ 42.412405] page:ffffea000025a780 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 |
| [ 42.413298] flags: 0x100000000008100(slab|head) |
| [ 42.413729] raw: 0100000000008100 0000000000000000 0000000000000000 00000001800c000c |
| [ 42.414387] raw: ffffea00002a9500 0000000900000007 ffff88000c401280 0000000000000000 |
| [ 42.415074] page dumped because: kasan: bad access detected |
| [ 42.415604] |
| [ 42.415757] Memory state around the buggy address: |
| [ 42.416222] ffff88000969e880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
| [ 42.416904] ffff88000969e900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
| [ 42.417591] >ffff88000969e980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc |
| [ 42.418273] ^ |
| [ 42.418588] ffff88000969ea00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb |
| [ 42.419273] ffff88000969ea80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb |
| [ 42.419882] ================================================================== |
| |
| Reported-by: Andrey Konovalov <andreyknvl@google.com> |
| Signed-off-by: Craig Gallek <kraig@google.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| net/ipv6/ip6_offload.c | 2 ++ |
| net/ipv6/ip6_output.c | 4 ++++ |
| net/ipv6/output_core.c | 14 ++++++++------ |
| net/ipv6/udp_offload.c | 2 ++ |
| 4 files changed, 16 insertions(+), 6 deletions(-) |
| |
| --- a/net/ipv6/ip6_offload.c |
| +++ b/net/ipv6/ip6_offload.c |
| @@ -117,6 +117,8 @@ static struct sk_buff *ipv6_gso_segment( |
| |
| if (udpfrag) { |
| unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr); |
| + if (unfrag_ip6hlen < 0) |
| + return ERR_PTR(unfrag_ip6hlen); |
| fptr = (struct frag_hdr *)((u8 *)ipv6h + unfrag_ip6hlen); |
| fptr->frag_off = htons(offset); |
| if (skb->next) |
| --- a/net/ipv6/ip6_output.c |
| +++ b/net/ipv6/ip6_output.c |
| @@ -587,6 +587,10 @@ int ip6_fragment(struct net *net, struct |
| u8 *prevhdr, nexthdr = 0; |
| |
| hlen = ip6_find_1stfragopt(skb, &prevhdr); |
| + if (hlen < 0) { |
| + err = hlen; |
| + goto fail; |
| + } |
| nexthdr = *prevhdr; |
| |
| mtu = ip6_skb_dst_mtu(skb); |
| --- a/net/ipv6/output_core.c |
| +++ b/net/ipv6/output_core.c |
| @@ -79,14 +79,13 @@ EXPORT_SYMBOL(ipv6_select_ident); |
| int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr) |
| { |
| u16 offset = sizeof(struct ipv6hdr); |
| - struct ipv6_opt_hdr *exthdr = |
| - (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1); |
| unsigned int packet_len = skb_tail_pointer(skb) - |
| skb_network_header(skb); |
| int found_rhdr = 0; |
| *nexthdr = &ipv6_hdr(skb)->nexthdr; |
| |
| - while (offset + 1 <= packet_len) { |
| + while (offset <= packet_len) { |
| + struct ipv6_opt_hdr *exthdr; |
| |
| switch (**nexthdr) { |
| |
| @@ -107,13 +106,16 @@ int ip6_find_1stfragopt(struct sk_buff * |
| return offset; |
| } |
| |
| - offset += ipv6_optlen(exthdr); |
| - *nexthdr = &exthdr->nexthdr; |
| + if (offset + sizeof(struct ipv6_opt_hdr) > packet_len) |
| + return -EINVAL; |
| + |
| exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) + |
| offset); |
| + offset += ipv6_optlen(exthdr); |
| + *nexthdr = &exthdr->nexthdr; |
| } |
| |
| - return offset; |
| + return -EINVAL; |
| } |
| EXPORT_SYMBOL(ip6_find_1stfragopt); |
| |
| --- a/net/ipv6/udp_offload.c |
| +++ b/net/ipv6/udp_offload.c |
| @@ -91,6 +91,8 @@ static struct sk_buff *udp6_ufo_fragment |
| * bytes to insert fragment header. |
| */ |
| unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr); |
| + if (unfrag_ip6hlen < 0) |
| + return ERR_PTR(unfrag_ip6hlen); |
| nexthdr = *prevhdr; |
| *prevhdr = NEXTHDR_FRAGMENT; |
| unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) + |