Commit d7efc6c1 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: remove hlist_nulls_add_tail_rcu()

Alexander Potapenko reported use of uninitialized memory [1]

This happens when inserting a request socket into TCP ehash,
in __sk_nulls_add_node_rcu(), since sk_reuseport is not initialized.

Bug was added by commit d894ba18 ("soreuseport: fix ordering for
mixed v4/v6 sockets")

Note that d296ba60 ("soreuseport: Resolve merge conflict for v4/v6
ordering fix") missed the opportunity to get rid of
hlist_nulls_add_tail_rcu() :

Both UDP sockets and TCP/DCCP listeners no longer use
__sk_nulls_add_node_rcu() for their hash insertion.

Since all other sockets have unique 4-tuple, the reuseport status
has no special meaning, so we can always use hlist_nulls_add_head_rcu()
for them and save few cycles/instructions.


BUG: KMSAN: use of uninitialized memory in inet_ehash_insert+0xd40/0x1050
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.13.0+ #3288
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16
 dump_stack+0x185/0x1d0 lib/dump_stack.c:52
 kmsan_report+0x13f/0x1c0 mm/kmsan/kmsan.c:1016
 __msan_warning_32+0x69/0xb0 mm/kmsan/kmsan_instr.c:766
 __sk_nulls_add_node_rcu ./include/net/sock.h:684
 inet_ehash_insert+0xd40/0x1050 net/ipv4/inet_hashtables.c:413
 reqsk_queue_hash_req net/ipv4/inet_connection_sock.c:754
 inet_csk_reqsk_queue_hash_add+0x1cc/0x300 net/ipv4/inet_connection_sock.c:765
 tcp_conn_request+0x31e7/0x36f0 net/ipv4/tcp_input.c:6414
 tcp_v4_conn_request+0x16d/0x220 net/ipv4/tcp_ipv4.c:1314
 tcp_rcv_state_process+0x42a/0x7210 net/ipv4/tcp_input.c:5917
 tcp_v4_do_rcv+0xa6a/0xcd0 net/ipv4/tcp_ipv4.c:1483
 tcp_v4_rcv+0x3de0/0x4ab0 net/ipv4/tcp_ipv4.c:1763
 ip_local_deliver_finish+0x6bb/0xcb0 net/ipv4/ip_input.c:216
 NF_HOOK ./include/linux/netfilter.h:248
 ip_local_deliver+0x3fa/0x480 net/ipv4/ip_input.c:257
 dst_input ./include/net/dst.h:477
 ip_rcv_finish+0x6fb/0x1540 net/ipv4/ip_input.c:397
 NF_HOOK ./include/linux/netfilter.h:248
 ip_rcv+0x10f6/0x15c0 net/ipv4/ip_input.c:488
 __netif_receive_skb_core+0x36f6/0x3f60 net/core/dev.c:4298
 __netif_receive_skb net/core/dev.c:4336
 netif_receive_skb_internal+0x63c/0x19c0 net/core/dev.c:4497
 napi_skb_finish net/core/dev.c:4858
 napi_gro_receive+0x629/0xa50 net/core/dev.c:4889
 e1000_receive_skb drivers/net/ethernet/intel/e1000/e1000_main.c:4018
 e1000_clean+0x43aa/0x5970 drivers/net/ethernet/intel/e1000/e1000_main.c:3819
 napi_poll net/core/dev.c:5500
 net_rx_action+0x73c/0x1820 net/core/dev.c:5566
 __do_softirq+0x4b4/0x8dd kernel/softirq.c:284
 invoke_softirq kernel/softirq.c:364
 irq_exit+0x203/0x240 kernel/softirq.c:405
 exiting_irq+0xe/0x10 ./arch/x86/include/asm/apic.h:638
 do_IRQ+0x15e/0x1a0 arch/x86/kernel/irq.c:263

Fixes: d894ba18 ("soreuseport: fix ordering for mixed v4/v6 sockets")
Fixes: d296ba60

 ("soreuseport: Resolve merge conflict for v4/v6 ordering fix")
Signed-off-by: default avatarEric Dumazet <>
Reported-by: default avatarAlexander Potapenko <>
Acked-by: default avatarCraig Gallek <>
Signed-off-by: default avatarDavid S. Miller <>
parent a5266440
......@@ -100,44 +100,6 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
first->pprev = &n->next;
* hlist_nulls_add_tail_rcu
* @n: the element to add to the hash list.
* @h: the list to add to.
* Description:
* Adds the specified element to the end of the specified hlist_nulls,
* while permitting racing traversals. NOTE: tail insertion requires
* list traversal.
* The caller must take whatever precautions are necessary
* (such as holding appropriate locks) to avoid racing
* with another list-mutation primitive, such as hlist_nulls_add_head_rcu()
* or hlist_nulls_del_rcu(), running on this same list.
* However, it is perfectly legal to run concurrently with
* the _rcu list-traversal primitives, such as
* hlist_nulls_for_each_entry_rcu(), used to prevent memory-consistency
* problems on Alpha CPUs. Regardless of the type of CPU, the
* list-traversal primitive must be guarded by rcu_read_lock().
static inline void hlist_nulls_add_tail_rcu(struct hlist_nulls_node *n,
struct hlist_nulls_head *h)
struct hlist_nulls_node *i, *last = NULL;
for (i = hlist_nulls_first_rcu(h); !is_a_nulls(i);
i = hlist_nulls_next_rcu(i))
last = i;
if (last) {
n->next = last->next;
n->pprev = &last->next;
rcu_assign_pointer(hlist_nulls_next_rcu(last), n);
} else {
hlist_nulls_add_head_rcu(n, h);
* hlist_nulls_for_each_entry_rcu - iterate over rcu list of given type
* @tpos: the type * to use as a loop cursor.
......@@ -685,11 +685,7 @@ static inline void sk_add_node_rcu(struct sock *sk, struct hlist_head *list)
static inline void __sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list)
if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
sk->sk_family == AF_INET6)
hlist_nulls_add_tail_rcu(&sk->sk_nulls_node, list);
hlist_nulls_add_head_rcu(&sk->sk_nulls_node, list);
hlist_nulls_add_head_rcu(&sk->sk_nulls_node, list);
static inline void sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list)
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