From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7A7F526656D for ; Mon, 21 Sep 2026 06:34:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789972494; cv=none; b=h0MjuoqhO4Tr4QmsBPHSQbEmeObbfWf27pz43om9FI/SNNKgMobvP7dKPnlbd4nJMVXcBT+73KlSIcvZE7qCombcRWIfCQsaoBxVdxyBrAh08N9347j917YowLB4RNuuK6A3WGudx5hBk+8FuKuFBNZBajsdRjZpLT53VlOhJvE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789972494; c=relaxed/simple; bh=tzHXtSDyKoqlRcC2fF99+d0VGCnqq37KuyiMMgIOk4o=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mOU7VFsTtiibPh/KNfyJM9OczZ+VUOMjA01NwI2PIaa6LM5yKo0Dh8EFXK1HKuQVy/CU50YLZ+EJnznJMGKTY7FXaJtTBXZxiaQ8ynhzUjhTiW0VU+Jqd1E7lvrBeq85E6ztFFbqUzBZGaODYCfWJ+fIIaWIZ9suJkAqK9x3Kds= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=IpTnWZxv; arc=none smtp.client-ip=91.218.175.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="IpTnWZxv" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=tzHXtSDyKoqlRcC2fF99+d0VGCnqq37KuyiMMgIOk4o=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1789972490; v=1; x=1790577290; b=IpTnWZxvWGOlde77JeVjqNrRBvENzJVxijGKg905gNiwdPC+O3gYHVkTqzPcwM0KpxrBb72O 96JWITrH8az/fHGHdr55GtSR/vK+YE3ADhJB0ncOFs96RyQkNnp4yEKs22Wf6Ei9TV6JWKmmjFI yHDVQOcZUHaMIHf+Qic7+CvE= X-Envelope-To: linux-kernel@vger.kernel.org Received: by mta10.migadu.com with ESMTPS id 4eb82a119267221f; Mon, 21 Sep 2026 06:34:50 +0000 X-Mizu-Trace-ID: 4eb82a119267221f X-Migadu-Flow: FLOW_OUT Date: Mon, 21 Sep 2026 14:34:37 +0800 From: Hangbin Liu To: Hui Peng Cc: Andrea Mayer , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , David Lebrun , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH net v2] ipv6: sr: enforce exact attribute length for SEG6_ATTR_DST Message-ID: References: <20260921044025.1535982-1-benquike@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260921044025.1535982-1-benquike@gmail.com> On Mon, Sep 21, 2026 at 04:40:25AM +0000, Hui Peng wrote: > In seg6_genl_policy, SEG6_ATTR_DST is defined with .type = NLA_BINARY and > .len = sizeof(struct in6_addr). For NLA_BINARY, .len only enforces the > maximum payload length and permits shorter payloads (e.g., 0 bytes). > When seg6_genl_set_tunsrc() copies sizeof(struct in6_addr) bytes via > kmemdup(val, sizeof(*val), GFP_KERNEL), a short SEG6_ATTR_DST attribute > triggers a 16-byte out-of-bounds read past skb->tail into uninitialized > skb->head memory, which is stored in sdata->tun_src and leaked back to > userspace via SEG6_CMD_GET_TUNSRC. > > Switch SEG6_ATTR_DST in seg6_genl_policy to > NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)) so that generic netlink > validation rejects any attribute whose length is not exactly > sizeof(struct in6_addr) with -ERANGE. > > Tested in QEMU against Linux 7.3.0-rc3 by sending a SEG6_CMD_SET_TUNSRC > Generic Netlink message with a 0-byte SEG6_ATTR_DST attribute followed > by SEG6_CMD_GET_TUNSRC. On the unfixed kernel, SEG6_CMD_SET_TUNSRC > succeeds (err = 0) and SEG6_CMD_GET_TUNSRC leaks 16 bytes of > uninitialized kernel heap memory (tun_src = > 836a61ecc4d25a1042a8d60411cfb378); with this patch applied, > SEG6_CMD_SET_TUNSRC is rejected by netlink policy validation with > -ERANGE (-34) and tun_src remains zeroed. > > Fixes: 915d7e5e5930 ("ipv6: sr: add code base for control plane support of SR-IPv6") > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Hui Peng > --- > Changes in v2: > - Drop the redundant nla_len(info->attrs[SEG6_ATTR_DST]) != > sizeof(struct in6_addr) check in seg6_genl_set_tunsrc() since > NLA_POLICY_EXACT_LEN() in seg6_genl_policy already enforces the exact > length, as pointed out by Hangbin Liu. > > net/ipv6/seg6.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c > index 62a7eb779202..8c2b156c227a 100644 > --- a/net/ipv6/seg6.c > +++ b/net/ipv6/seg6.c > @@ -138,8 +138,8 @@ void seg6_icmp_srh(struct sk_buff *skb, struct inet6_skb_parm *opt) > static struct genl_family seg6_genl_family; > > static const struct nla_policy seg6_genl_policy[SEG6_ATTR_MAX + 1] = { > - [SEG6_ATTR_DST] = { .type = NLA_BINARY, > - .len = sizeof(struct in6_addr) }, > + [SEG6_ATTR_DST] = > + NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)), > [SEG6_ATTR_DSTLEN] = { .type = NLA_S32, }, > [SEG6_ATTR_HMACKEYID] = { .type = NLA_U32, }, > [SEG6_ATTR_SECRET] = { .type = NLA_BINARY, }, > -- > 2.49.0 Reviewed-by: Hangbin Liu