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 533BD3922F for ; Wed, 7 Jun 2023 20:57:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C6E97C4339C; Wed, 7 Jun 2023 20:57:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1686171474; bh=nUtwn1Z7kC3XfG1P+VdAVP3PCrcftdAWnDBPgsRheEM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=p0R2c7C0hBzIhwREl+XBF8KzN7fWfkPVGrW0AqXc/AoDmAmHGPOormeYQXelbLxwQ f2FH8oR6koxUQ/Bhqu+X1iQh5i+h0aYbU1iupLdeelPhVAK+YGWIiXl7ZIH+mums84 bELOPL852PtAQ0AX20GzeugF5ZR18R4L1xuVRH4E= 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 5.15 032/159] udp6: Fix race condition in udp6_sendmsg & connect Date: Wed, 7 Jun 2023 22:15:35 +0200 Message-ID: <20230607200904.719735977@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230607200903.652580797@linuxfoundation.org> References: <20230607200903.652580797@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(-) --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2165,7 +2165,6 @@ void sk_setup_caps(struct sock *sk, stru { 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; @@ -2180,6 +2179,7 @@ void sk_setup_caps(struct sock *sk, stru } } sk->sk_gso_max_segs = max_segs; + sk_dst_set(sk, dst); } EXPORT_SYMBOL_GPL(sk_setup_caps);