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 80EC743DA48; Mon, 20 Apr 2026 13:30:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776691800; cv=none; b=bkNaDJKgimmBdx2DdKFxGo4c6e8g5ta5lXghT87TrQe+T9B03Z5ZxGlOWwkGUHwQfF6bSlu1YHPwuDhLtCkjSy29WGCW9ilyL01X3e3n6LgkBhNz4g9Wjw9l+7Zn2/+3yY3ViUACPNivcNNOlBSxJq50xYMCSenOh4125An5Xo8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776691800; c=relaxed/simple; bh=9gmm8hE1FEqgRq6dxa1smE9VP0HArrH4lZWol0kVoBQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oa2v4lNjtv8ed8kXS1j7eQSJXRwJ3QqaWJwQ9x5nLfivDHUWvknp3JJjW3uB31hZEX8XK3IbH2cW383+CgCVNY+WY3fvsJjr61/QFnmFRVst0ryT0FbtSHFxXsCSgFSgg2UDCSONyLOlg5Y+Ttw3Ye/xe5ddWB7qmyy6t7qhPKc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CZC7rsRp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CZC7rsRp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2795FC2BCB7; Mon, 20 Apr 2026 13:29:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776691800; bh=9gmm8hE1FEqgRq6dxa1smE9VP0HArrH4lZWol0kVoBQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CZC7rsRpp4kR7W1uWS2fvSPp2BpSFCNG0of0kKwwJNIK+RwysAf0/boeH4znnUqm2 bIJd2QcGMtHk6kZnnRAmOK4wSAmtrk8PEQHvRjw40ULAdzeEepLtXCVr0/0noeED5P RQpysUNYU8khSsZahtQFgczSmOhvV5HcRcpKQCB9yiaZD0tDi0XbmRH4WChqfI8Ndh TjuRL5qKBOHkReLNvzAbgDLK+36CmRaWVAWtCJEqeozrOPu0VKBDp0PUKzA6pRnbif XP6IJe9vreQlUNp4BrtVesT6Pue/G/VZO2fY67WxsL2mSjhmegwNgIOMiA3qRnN1Mv 3H3k254vDv//Q== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Eric Dumazet , Yiming Qian , Justin Iurman , Jakub Kicinski , Sasha Levin , davem@davemloft.net, dsahern@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH AUTOSEL 6.18] ipv6: ioam: fix potential NULL dereferences in __ioam6_fill_trace_data() Date: Mon, 20 Apr 2026 09:19:55 -0400 Message-ID: <20260420132314.1023554-201-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260420132314.1023554-1-sashal@kernel.org> References: <20260420132314.1023554-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.18.23 Content-Transfer-Encoding: 8bit From: Eric Dumazet [ Upstream commit 4e65a8b8daa18d63255ec58964dd192c7fdd9f8b ] We need to check __in6_dev_get() for possible NULL value, as suggested by Yiming Qian. Also add skb_dst_dev_rcu() instead of skb_dst_dev(), and two missing READ_ONCE(). Note that @dev can't be NULL. Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace") Reported-by: Yiming Qian Signed-off-by: Eric Dumazet Reviewed-by: Justin Iurman Link: https://patch.msgid.link/20260402101732.1188059-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- LLM Generated explanations, may be completely bogus: Error: Failed to generate final synthesis net/ipv6/ioam6.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) diff --git a/net/ipv6/ioam6.c b/net/ipv6/ioam6.c index 8db7f965696aa..12350e1e18bde 100644 --- a/net/ipv6/ioam6.c +++ b/net/ipv6/ioam6.c @@ -710,7 +710,9 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, struct ioam6_schema *sc, unsigned int sclen, bool is_input) { - struct net_device *dev = skb_dst_dev(skb); + /* Note: skb_dst_dev_rcu() can't be NULL at this point. */ + struct net_device *dev = skb_dst_dev_rcu(skb); + struct inet6_dev *i_skb_dev, *idev; struct timespec64 ts; ktime_t tstamp; u64 raw64; @@ -721,13 +723,16 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, data = trace->data + trace->remlen * 4 - trace->nodelen * 4 - sclen * 4; + i_skb_dev = skb->dev ? __in6_dev_get(skb->dev) : NULL; + idev = __in6_dev_get(dev); + /* hop_lim and node_id */ if (trace->type.bit0) { byte = ipv6_hdr(skb)->hop_limit; if (is_input) byte--; - raw32 = dev_net(dev)->ipv6.sysctl.ioam6_id; + raw32 = READ_ONCE(dev_net(dev)->ipv6.sysctl.ioam6_id); *(__be32 *)data = cpu_to_be32((byte << 24) | raw32); data += sizeof(__be32); @@ -735,18 +740,18 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, /* ingress_if_id and egress_if_id */ if (trace->type.bit1) { - if (!skb->dev) + if (!i_skb_dev) raw16 = IOAM6_U16_UNAVAILABLE; else - raw16 = (__force u16)READ_ONCE(__in6_dev_get(skb->dev)->cnf.ioam6_id); + raw16 = (__force u16)READ_ONCE(i_skb_dev->cnf.ioam6_id); *(__be16 *)data = cpu_to_be16(raw16); data += sizeof(__be16); - if (dev->flags & IFF_LOOPBACK) + if ((dev->flags & IFF_LOOPBACK) || !idev) raw16 = IOAM6_U16_UNAVAILABLE; else - raw16 = (__force u16)READ_ONCE(__in6_dev_get(dev)->cnf.ioam6_id); + raw16 = (__force u16)READ_ONCE(idev->cnf.ioam6_id); *(__be16 *)data = cpu_to_be16(raw16); data += sizeof(__be16); @@ -822,7 +827,7 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, if (is_input) byte--; - raw64 = dev_net(dev)->ipv6.sysctl.ioam6_id_wide; + raw64 = READ_ONCE(dev_net(dev)->ipv6.sysctl.ioam6_id_wide); *(__be64 *)data = cpu_to_be64(((u64)byte << 56) | raw64); data += sizeof(__be64); @@ -830,18 +835,18 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, /* ingress_if_id and egress_if_id (wide) */ if (trace->type.bit9) { - if (!skb->dev) + if (!i_skb_dev) raw32 = IOAM6_U32_UNAVAILABLE; else - raw32 = READ_ONCE(__in6_dev_get(skb->dev)->cnf.ioam6_id_wide); + raw32 = READ_ONCE(i_skb_dev->cnf.ioam6_id_wide); *(__be32 *)data = cpu_to_be32(raw32); data += sizeof(__be32); - if (dev->flags & IFF_LOOPBACK) + if ((dev->flags & IFF_LOOPBACK) || !idev) raw32 = IOAM6_U32_UNAVAILABLE; else - raw32 = READ_ONCE(__in6_dev_get(dev)->cnf.ioam6_id_wide); + raw32 = READ_ONCE(idev->cnf.ioam6_id_wide); *(__be32 *)data = cpu_to_be32(raw32); data += sizeof(__be32); -- 2.53.0