This is a note to let you know that I've just added the patch titled
dccp/tcp: Avoid negative sk_forward_alloc by ipv6_pinfo.pktoptions.
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dccp-tcp-avoid-negative-sk_forward_alloc-by-ipv6_pinfo.pktoptions.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ca43ccf41224b023fc290073d5603a755fd12eed Mon Sep 17 00:00:00 2001
From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Thu, 9 Feb 2023 16:22:01 -0800
Subject: dccp/tcp: Avoid negative sk_forward_alloc by ipv6_pinfo.pktoptions.
From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
commit ca43ccf41224b023fc290073d5603a755fd12eed upstream.
Eric Dumazet pointed out [0] that when we call skb_set_owner_r()
for ipv6_pinfo.pktoptions, sk_rmem_schedule() has not been called,
resulting in a negative sk_forward_alloc.
We add a new helper which clones a skb and sets its owner only
when sk_rmem_schedule() succeeds.
Note that we move skb_set_owner_r() forward in (dccp|tcp)_v6_do_rcv()
because tcp_send_synack() can make sk_forward_alloc negative before
ipv6_opt_accepted() in the crossed SYN-ACK or self-connect() cases.
[0]: https://lore.kernel.org/netdev/CANn89iK9oc20Jdi_41jb9URdF210r7d1Y-+uypbMSbOfY6jqrg@xxxxxxxxxxxxxx/
Fixes: 323fbd0edf3f ("net: dccp: Add handling of IPV6_PKTOPTIONS to dccp_v6_do_rcv()")
Fixes: 3df80d9320bc ("[DCCP]: Introduce DCCPv6")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/sock.h | 13 +++++++++++++
net/dccp/ipv6.c | 7 ++-----
net/ipv6/tcp_ipv6.c | 10 +++-------
3 files changed, 18 insertions(+), 12 deletions(-)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2167,6 +2167,19 @@ static inline __must_check bool skb_set_
return false;
}
+static inline struct sk_buff *skb_clone_and_charge_r(struct sk_buff *skb, struct sock *sk)
+{
+ skb = skb_clone(skb, sk_gfp_mask(sk, GFP_ATOMIC));
+ if (skb) {
+ if (sk_rmem_schedule(sk, skb, skb->truesize)) {
+ skb_set_owner_r(skb, sk);
+ return skb;
+ }
+ __kfree_skb(skb);
+ }
+ return NULL;
+}
+
void sk_reset_timer(struct sock *sk, struct timer_list *timer,
unsigned long expires);
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -541,11 +541,9 @@ static struct sock *dccp_v6_request_recv
*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL);
/* Clone pktoptions received with SYN, if we own the req */
if (*own_req && ireq->pktopts) {
- newnp->pktoptions = skb_clone(ireq->pktopts, GFP_ATOMIC);
+ newnp->pktoptions = skb_clone_and_charge_r(ireq->pktopts, newsk);
consume_skb(ireq->pktopts);
ireq->pktopts = NULL;
- if (newnp->pktoptions)
- skb_set_owner_r(newnp->pktoptions, newsk);
}
return newsk;
@@ -605,7 +603,7 @@ static int dccp_v6_do_rcv(struct sock *s
--ANK (980728)
*/
if (np->rxopt.all)
- opt_skb = skb_clone(skb, GFP_ATOMIC);
+ opt_skb = skb_clone_and_charge_r(skb, sk);
if (sk->sk_state == DCCP_OPEN) { /* Fast path */
if (dccp_rcv_established(sk, skb, dccp_hdr(skb), skb->len))
@@ -669,7 +667,6 @@ ipv6_pktoptions:
np->flow_label = ip6_flowlabel(ipv6_hdr(opt_skb));
if (ipv6_opt_accepted(sk, opt_skb,
&DCCP_SKB_CB(opt_skb)->header.h6)) {
- skb_set_owner_r(opt_skb, sk);
memmove(IP6CB(opt_skb),
&DCCP_SKB_CB(opt_skb)->header.h6,
sizeof(struct inet6_skb_parm));
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1318,14 +1318,11 @@ static struct sock *tcp_v6_syn_recv_sock
/* Clone pktoptions received with SYN, if we own the req */
if (ireq->pktopts) {
- newnp->pktoptions = skb_clone(ireq->pktopts,
- sk_gfp_mask(sk, GFP_ATOMIC));
+ newnp->pktoptions = skb_clone_and_charge_r(ireq->pktopts, newsk);
consume_skb(ireq->pktopts);
ireq->pktopts = NULL;
- if (newnp->pktoptions) {
+ if (newnp->pktoptions)
tcp_v6_restore_cb(newnp->pktoptions);
- skb_set_owner_r(newnp->pktoptions, newsk);
- }
}
} else {
if (!req_unhash && found_dup_sk) {
@@ -1393,7 +1390,7 @@ static int tcp_v6_do_rcv(struct sock *sk
--ANK (980728)
*/
if (np->rxopt.all)
- opt_skb = skb_clone(skb, sk_gfp_mask(sk, GFP_ATOMIC));
+ opt_skb = skb_clone_and_charge_r(skb, sk);
if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
struct dst_entry *dst;
@@ -1475,7 +1472,6 @@ ipv6_pktoptions:
if (np->repflow)
np->flow_label = ip6_flowlabel(ipv6_hdr(opt_skb));
if (ipv6_opt_accepted(sk, opt_skb, &TCP_SKB_CB(opt_skb)->header.h6)) {
- skb_set_owner_r(opt_skb, sk);
tcp_v6_restore_cb(opt_skb);
opt_skb = xchg(&np->pktoptions, opt_skb);
} else {
Patches currently in stable-queue which might be from kuniyu@xxxxxxxxxx are
queue-5.4/net-rose-fix-to-not-accept-on-connected-socket.patch
queue-5.4/netrom-fix-use-after-free-caused-by-accept-on-alread.patch
queue-5.4/dccp-tcp-avoid-negative-sk_forward_alloc-by-ipv6_pinfo.pktoptions.patch
