From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F3689370E4 for ; Wed, 7 Jun 2023 20:53:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74461C433D2; Wed, 7 Jun 2023 20:53:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1686171187; bh=SCjc7CYAyMtgmgFyc40w1KBliauxGPaJhtdo288q38A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X0dXxi8eFkjhUMUUr13u9Qg3P9Cvamxw3iq1GghDKv+0fzPcJyLwNEoNE3LF32Jp7 aTvPP67Xz2ngYtMojOq0ZOkHNkVxrfgmiHzQ5FZ424R5/o1/qTkbXelqLTtxmEE19/ 675ONC8UI3G40yibf/xlKysSxK2jpr7WpAdNJ4bo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vladislav Efanov , Paolo Abeni , "David S. Miller" , Sasha Levin Subject: [PATCH 5.4 23/99] udp6: Fix race condition in udp6_sendmsg & connect Date: Wed, 7 Jun 2023 22:16:15 +0200 Message-ID: <20230607200900.982590034@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230607200900.195572674@linuxfoundation.org> References: <20230607200900.195572674@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Vladislav Efanov [ Upstream commit 448a5ce1120c5bdbce1f1ccdabcd31c7d029f328 ] Syzkaller got the following report: BUG: KASAN: use-after-free in sk_setup_caps+0x621/0x690 net/core/sock.c:2018 Read of size 8 at addr ffff888027f82780 by task syz-executor276/3255 The function sk_setup_caps (called by ip6_sk_dst_store_flow-> ip6_dst_store) referenced already freed memory as this memory was freed by parallel task in udpv6_sendmsg->ip6_sk_dst_lookup_flow-> sk_dst_check. task1 (connect) task2 (udp6_sendmsg) sk_setup_caps->sk_dst_set | | sk_dst_check-> | sk_dst_set | dst_release sk_setup_caps references | to already freed dst_entry| The reason for this race condition is: sk_setup_caps() keeps using the dst after transferring the ownership to the dst cache. Found by Linux Verification Center (linuxtesting.org) with syzkaller. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Vladislav Efanov Signed-off-by: Paolo Abeni Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/core/sock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/sock.c b/net/core/sock.c index 7f6f1a0bf8a13..5e1dccbd61a60 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1938,7 +1938,6 @@ void sk_setup_caps(struct sock *sk, struct dst_entry *dst) { u32 max_segs = 1; - sk_dst_set(sk, dst); sk->sk_route_caps = dst->dev->features | sk->sk_route_forced_caps; if (sk->sk_route_caps & NETIF_F_GSO) sk->sk_route_caps |= NETIF_F_GSO_SOFTWARE; @@ -1953,6 +1952,7 @@ void sk_setup_caps(struct sock *sk, struct dst_entry *dst) } } sk->sk_gso_max_segs = max_segs; + sk_dst_set(sk, dst); } EXPORT_SYMBOL_GPL(sk_setup_caps); -- 2.39.2