From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 903B551AEEE; Wed, 30 Sep 2026 18:21:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790792461; cv=none; b=O6VwqWt8zQG0JSYerkF8prOzjKUhUtSfRyf226szAL1cRMse32aTsAna1+FvgVJopm0xtkwz4gP2j87YNHPejrXueWeRYXG/Rjx1vzVjm+DPG/y+MOoZwjACi0GW1JBZpsX3rUlzAIm02jFelGCtN6f6rzDb8LcUNKXhIZpkYu8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790792461; c=relaxed/simple; bh=Lc6SvIWG0WTTdV7cK/FGeLwYmdAkiZeuP920szhyMwQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OChRlith9qetaQkbEI3wwwYpwZkIQrJls88Cfzy6W8lW49iiTAuWI/rSJlZv5Sgb1SnLqLxkDExxS1qMNGmmiO04EUGGpE1OxHnCh4qHh5chKtjw3/Tb2zMJhbbWWzWKHvtA+tXpA9E6EezFZgEpS9xeWJwcqeLIPrrDVNkcv7w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=GQF+SMsV; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="GQF+SMsV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA31B1F000FF; Wed, 30 Sep 2026 18:20:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790792460; bh=IgsldSFwb6xbD9WyGkA2kHunRJwaIO1nNxuXYMSAIz0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GQF+SMsVWKQaHCrz28kiGfEpmAbLCcjuSmWzcnX4i/Jq4lIJVJaFe99h1dqpvo1bX WVXE3SblKS3FQQTdgLtDreurTmRyxvmaA94NVxmdyUo3cO7uG8rHzUpnxUnix78h8M R5lo5+e4EDNI12ZfCz+aA52a3xdgjBLlJQIX5QTE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , Shihuang Liu , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 664/752] net: skbuff: fix pull-bound underflow in skb_checksum_setup_ipv6() Date: Wed, 30 Sep 2026 17:28:54 +0200 Message-ID: <20260930152412.626363135@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shihuang Liu [ Upstream commit 3b4e0b0c008a8c1b474730248cd5b873026c74bd ] skb_maybe_pull_tail() subtracts skb_headlen(skb) from the unsigned max argument and passes the result to __pskb_pull_tail() as a signed int. The function does not ensure that max is at least skb_headlen(skb). This can happen while parsing IPv6 extension headers when an skb already has a linear area larger than MAX_IPV6_HDR_LEN. Once the parser needs data beyond the linear area, max - skb_headlen(skb) wraps and is converted to a negative delta. __pskb_pull_tail() then passes that negative length to skb_copy_bits(), where it can become a very large copy length. Pass the requested length itself as the pull bound at the three extension-header call sites, so the delta can no longer go negative. Fixes: 1431fb31ecba ("xen-netback: fix fragment detection in checksum setup") Suggested-by: Eric Dumazet Signed-off-by: Shihuang Liu Link: https://patch.msgid.link/20260919133604.50948-1-shlomojune6@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/core/skbuff.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 312fe0372829b..f35d32561c36a 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5261,7 +5261,8 @@ static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate) err = skb_maybe_pull_tail(skb, off + sizeof(struct ipv6_opt_hdr), - MAX_IPV6_HDR_LEN); + off + + sizeof(struct ipv6_opt_hdr)); if (err < 0) goto out; @@ -5276,7 +5277,8 @@ static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate) err = skb_maybe_pull_tail(skb, off + sizeof(struct ip_auth_hdr), - MAX_IPV6_HDR_LEN); + off + + sizeof(struct ip_auth_hdr)); if (err < 0) goto out; @@ -5291,7 +5293,8 @@ static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate) err = skb_maybe_pull_tail(skb, off + sizeof(struct frag_hdr), - MAX_IPV6_HDR_LEN); + off + + sizeof(struct frag_hdr)); if (err < 0) goto out; -- 2.53.0