From: Eric Dumazet <edumazet@google.com> mainline inclusion from mainline-v6.14-rc3 commit 628e6d18930bbd21f2d4562228afe27694f66da9 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBPC6A CVE: CVE-2025-21764 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- ndisc_alloc_skb() can be called without RTNL or RCU being held. Add RCU protection to avoid possible UAF. Fixes: de09334b9326 ("ndisc: Introduce ndisc_alloc_skb() helper.") Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://patch.msgid.link/20250207135841.1948589-3-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/ipv6/ndisc.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index 673a4a932f2a..5c1d092711aa 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -397,15 +397,11 @@ static struct sk_buff *ndisc_alloc_skb(struct net_device *dev, { int hlen = LL_RESERVED_SPACE(dev); int tlen = dev->needed_tailroom; - struct sock *sk = dev_net(dev)->ipv6.ndisc_sk; struct sk_buff *skb; skb = alloc_skb(hlen + sizeof(struct ipv6hdr) + len + tlen, GFP_ATOMIC); - if (!skb) { - ND_PRINTK(0, err, "ndisc: %s failed to allocate an skb\n", - __func__); + if (!skb) return NULL; - } skb->protocol = htons(ETH_P_IPV6); skb->dev = dev; @@ -416,7 +412,9 @@ static struct sk_buff *ndisc_alloc_skb(struct net_device *dev, /* Manually assign socket ownership as we avoid calling * sock_alloc_send_pskb() to bypass wmem buffer limits */ - skb_set_owner_w(skb, sk); + rcu_read_lock(); + skb_set_owner_w(skb, dev_net_rcu(dev)->ipv6.ndisc_sk); + rcu_read_unlock(); return skb; } -- 2.25.1