From: Eric Dumazet <edumazet@google.com> stable inclusion from stable-v6.6.48 commit 124b428fe28064c809e4237b0b38e97200a8a4a8 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAOXZA CVE: CVE-2024-44985 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... --------------------------- [ Upstream commit 2d5ff7e339d04622d8282661df36151906d0e1c7 ] If skb_expand_head() returns NULL, skb has been freed and the associated dst/idev could also have been freed. We must use rcu_read_lock() to prevent a possible UAF. Fixes: 0c9f227bee11 ("ipv6: use skb_expand_head in ip6_xmit") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Vasily Averin <vasily.averin@linux.dev> Reviewed-by: David Ahern <dsahern@kernel.org> Link: https://patch.msgid.link/20240820160859.3786976-4-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com> --- net/ipv6/ip6_output.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index db8d0e1..290ca82 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -277,11 +277,15 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, head_room += opt->opt_nflen + opt->opt_flen; if (unlikely(head_room > skb_headroom(skb))) { + /* Make sure idev stays alive */ + rcu_read_lock(); skb = skb_expand_head(skb, head_room); if (!skb) { IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); + rcu_read_unlock(); return -ENOBUFS; } + rcu_read_unlock(); } if (opt) { -- 2.9.5