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Subject[PATCH 4.10 33/63] dccp: fix use-after-free in dccp_feat_activate_values
Date
4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@google.com>


[ Upstream commit 62f8f4d9066c1c6f2474845d1ca7e2891f2ae3fd ]

Dmitry reported crashes in DCCP stack [1]

Problem here is that when I got rid of listener spinlock, I missed the
fact that DCCP stores a complex state in struct dccp_request_sock,
while TCP does not.

Since multiple cpus could access it at the same time, we need to add
protection.

[1]
BUG: KASAN: use-after-free in dccp_feat_activate_values+0x967/0xab0
net/dccp/feat.c:1541 at addr ffff88003713be68
Read of size 8 by task syz-executor2/8457
CPU: 2 PID: 8457 Comm: syz-executor2 Not tainted 4.10.0-rc7+ #127
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:15 [inline]
dump_stack+0x292/0x398 lib/dump_stack.c:51
kasan_object_err+0x1c/0x70 mm/kasan/report.c:162
print_address_description mm/kasan/report.c:200 [inline]
kasan_report_error mm/kasan/report.c:289 [inline]
kasan_report.part.1+0x20e/0x4e0 mm/kasan/report.c:311
kasan_report mm/kasan/report.c:332 [inline]
__asan_report_load8_noabort+0x29/0x30 mm/kasan/report.c:332
dccp_feat_activate_values+0x967/0xab0 net/dccp/feat.c:1541
dccp_create_openreq_child+0x464/0x610 net/dccp/minisocks.c:121
dccp_v6_request_recv_sock+0x1f6/0x1960 net/dccp/ipv6.c:457
dccp_check_req+0x335/0x5a0 net/dccp/minisocks.c:186
dccp_v6_rcv+0x69e/0x1d00 net/dccp/ipv6.c:711
ip6_input_finish+0x46d/0x17a0 net/ipv6/ip6_input.c:279
NF_HOOK include/linux/netfilter.h:257 [inline]
ip6_input+0xdb/0x590 net/ipv6/ip6_input.c:322
dst_input include/net/dst.h:507 [inline]
ip6_rcv_finish+0x289/0x890 net/ipv6/ip6_input.c:69
NF_HOOK include/linux/netfilter.h:257 [inline]
ipv6_rcv+0x12ec/0x23d0 net/ipv6/ip6_input.c:203
__netif_receive_skb_core+0x1ae5/0x3400 net/core/dev.c:4190
__netif_receive_skb+0x2a/0x170 net/core/dev.c:4228
process_backlog+0xe5/0x6c0 net/core/dev.c:4839
napi_poll net/core/dev.c:5202 [inline]
net_rx_action+0xe70/0x1900 net/core/dev.c:5267
__do_softirq+0x2fb/0xb7d kernel/softirq.c:284
do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:902
</IRQ>
do_softirq.part.17+0x1e8/0x230 kernel/softirq.c:328
do_softirq kernel/softirq.c:176 [inline]
__local_bh_enable_ip+0x1f2/0x200 kernel/softirq.c:181
local_bh_enable include/linux/bottom_half.h:31 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:971 [inline]
ip6_finish_output2+0xbb0/0x23d0 net/ipv6/ip6_output.c:123
ip6_finish_output+0x302/0x960 net/ipv6/ip6_output.c:148
NF_HOOK_COND include/linux/netfilter.h:246 [inline]
ip6_output+0x1cb/0x8d0 net/ipv6/ip6_output.c:162
ip6_xmit+0xcdf/0x20d0 include/net/dst.h:501
inet6_csk_xmit+0x320/0x5f0 net/ipv6/inet6_connection_sock.c:179
dccp_transmit_skb+0xb09/0x1120 net/dccp/output.c:141
dccp_xmit_packet+0x215/0x760 net/dccp/output.c:280
dccp_write_xmit+0x168/0x1d0 net/dccp/output.c:362
dccp_sendmsg+0x79c/0xb10 net/dccp/proto.c:796
inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:744
sock_sendmsg_nosec net/socket.c:635 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:645
SYSC_sendto+0x660/0x810 net/socket.c:1687
SyS_sendto+0x40/0x50 net/socket.c:1655
entry_SYSCALL_64_fastpath+0x1f/0xc2
RIP: 0033:0x4458b9
RSP: 002b:00007f8ceb77bb58 EFLAGS: 00000282 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000017 RCX: 00000000004458b9
RDX: 0000000000000023 RSI: 0000000020e60000 RDI: 0000000000000017
RBP: 00000000006e1b90 R08: 00000000200f9fe1 R09: 0000000000000020
R10: 0000000000008010 R11: 0000000000000282 R12: 00000000007080a8
R13: 0000000000000000 R14: 00007f8ceb77c9c0 R15: 00007f8ceb77c700
Object at ffff88003713be50, in cache kmalloc-64 size: 64
Allocated:
PID = 8446
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
save_stack+0x43/0xd0 mm/kasan/kasan.c:502
set_track mm/kasan/kasan.c:514 [inline]
kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:605
kmem_cache_alloc_trace+0x82/0x270 mm/slub.c:2738
kmalloc include/linux/slab.h:490 [inline]
dccp_feat_entry_new+0x214/0x410 net/dccp/feat.c:467
dccp_feat_push_change+0x38/0x220 net/dccp/feat.c:487
__feat_register_sp+0x223/0x2f0 net/dccp/feat.c:741
dccp_feat_propagate_ccid+0x22b/0x2b0 net/dccp/feat.c:949
dccp_feat_server_ccid_dependencies+0x1b3/0x250 net/dccp/feat.c:1012
dccp_make_response+0x1f1/0xc90 net/dccp/output.c:423
dccp_v6_send_response+0x4ec/0xc20 net/dccp/ipv6.c:217
dccp_v6_conn_request+0xaba/0x11b0 net/dccp/ipv6.c:377
dccp_rcv_state_process+0x51e/0x1650 net/dccp/input.c:606
dccp_v6_do_rcv+0x213/0x350 net/dccp/ipv6.c:632
sk_backlog_rcv include/net/sock.h:893 [inline]
__sk_receive_skb+0x36f/0xcc0 net/core/sock.c:479
dccp_v6_rcv+0xba5/0x1d00 net/dccp/ipv6.c:742
ip6_input_finish+0x46d/0x17a0 net/ipv6/ip6_input.c:279
NF_HOOK include/linux/netfilter.h:257 [inline]
ip6_input+0xdb/0x590 net/ipv6/ip6_input.c:322
dst_input include/net/dst.h:507 [inline]
ip6_rcv_finish+0x289/0x890 net/ipv6/ip6_input.c:69
NF_HOOK include/linux/netfilter.h:257 [inline]
ipv6_rcv+0x12ec/0x23d0 net/ipv6/ip6_input.c:203
__netif_receive_skb_core+0x1ae5/0x3400 net/core/dev.c:4190
__netif_receive_skb+0x2a/0x170 net/core/dev.c:4228
process_backlog+0xe5/0x6c0 net/core/dev.c:4839
napi_poll net/core/dev.c:5202 [inline]
net_rx_action+0xe70/0x1900 net/core/dev.c:5267
__do_softirq+0x2fb/0xb7d kernel/softirq.c:284
Freed:
PID = 15
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
save_stack+0x43/0xd0 mm/kasan/kasan.c:502
set_track mm/kasan/kasan.c:514 [inline]
kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:578
slab_free_hook mm/slub.c:1355 [inline]
slab_free_freelist_hook mm/slub.c:1377 [inline]
slab_free mm/slub.c:2954 [inline]
kfree+0xe8/0x2b0 mm/slub.c:3874
dccp_feat_entry_destructor.part.4+0x48/0x60 net/dccp/feat.c:418
dccp_feat_entry_destructor net/dccp/feat.c:416 [inline]
dccp_feat_list_pop net/dccp/feat.c:541 [inline]
dccp_feat_activate_values+0x57f/0xab0 net/dccp/feat.c:1543
dccp_create_openreq_child+0x464/0x610 net/dccp/minisocks.c:121
dccp_v6_request_recv_sock+0x1f6/0x1960 net/dccp/ipv6.c:457
dccp_check_req+0x335/0x5a0 net/dccp/minisocks.c:186
dccp_v6_rcv+0x69e/0x1d00 net/dccp/ipv6.c:711
ip6_input_finish+0x46d/0x17a0 net/ipv6/ip6_input.c:279
NF_HOOK include/linux/netfilter.h:257 [inline]
ip6_input+0xdb/0x590 net/ipv6/ip6_input.c:322
dst_input include/net/dst.h:507 [inline]
ip6_rcv_finish+0x289/0x890 net/ipv6/ip6_input.c:69
NF_HOOK include/linux/netfilter.h:257 [inline]
ipv6_rcv+0x12ec/0x23d0 net/ipv6/ip6_input.c:203
__netif_receive_skb_core+0x1ae5/0x3400 net/core/dev.c:4190
__netif_receive_skb+0x2a/0x170 net/core/dev.c:4228
process_backlog+0xe5/0x6c0 net/core/dev.c:4839
napi_poll net/core/dev.c:5202 [inline]
net_rx_action+0xe70/0x1900 net/core/dev.c:5267
__do_softirq+0x2fb/0xb7d kernel/softirq.c:284
Memory state around the buggy address:
ffff88003713bd00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88003713bd80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88003713be00: fc fc fc fc fc fc fc fc fc fc fb fb fb fb fb fb
^

Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/dccp.h | 1 +
net/dccp/minisocks.c | 24 ++++++++++++++++--------
2 files changed, 17 insertions(+), 8 deletions(-)

--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -163,6 +163,7 @@ struct dccp_request_sock {
__u64 dreq_isr;
__u64 dreq_gsr;
__be32 dreq_service;
+ spinlock_t dreq_lock;
struct list_head dreq_featneg;
__u32 dreq_timestamp_echo;
__u32 dreq_timestamp_time;
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -146,6 +146,13 @@ struct sock *dccp_check_req(struct sock
struct dccp_request_sock *dreq = dccp_rsk(req);
bool own_req;

+ /* TCP/DCCP listeners became lockless.
+ * DCCP stores complex state in its request_sock, so we need
+ * a protection for them, now this code runs without being protected
+ * by the parent (listener) lock.
+ */
+ spin_lock_bh(&dreq->dreq_lock);
+
/* Check for retransmitted REQUEST */
if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {

@@ -160,7 +167,7 @@ struct sock *dccp_check_req(struct sock
inet_rtx_syn_ack(sk, req);
}
/* Network Duplicate, discard packet */
- return NULL;
+ goto out;
}

DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
@@ -186,20 +193,20 @@ struct sock *dccp_check_req(struct sock

child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
req, &own_req);
- if (!child)
- goto listen_overflow;
-
- return inet_csk_complete_hashdance(sk, child, req, own_req);
+ if (child) {
+ child = inet_csk_complete_hashdance(sk, child, req, own_req);
+ goto out;
+ }

-listen_overflow:
- dccp_pr_debug("listen_overflow!\n");
DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
drop:
if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
req->rsk_ops->send_reset(sk, skb);

inet_csk_reqsk_queue_drop(sk, req);
- return NULL;
+out:
+ spin_unlock_bh(&dreq->dreq_lock);
+ return child;
}

EXPORT_SYMBOL_GPL(dccp_check_req);
@@ -250,6 +257,7 @@ int dccp_reqsk_init(struct request_sock
{
struct dccp_request_sock *dreq = dccp_rsk(req);

+ spin_lock_init(&dreq->dreq_lock);
inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport);
inet_rsk(req)->acked = 0;

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