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 F118251A15C; Wed, 30 Sep 2026 17:27:43 +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=1790789265; cv=none; b=De+Jo6Nr8MivaRMPsVssCB4e+dhrVQy4UBDGiMgDZgc+/63L2p6pwv1ncTw+FPAFqb45h4qmLaA9DqH7LdsI8iHKxRD8h9KJkTtnoTRRwfjyoQ4OtWdGbV2Y4TEpU1w/BkvrQT+sJGMFM6I07mprdhHWBHchf9bYwCovEFdM5BM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790789265; c=relaxed/simple; bh=50yJFwUXwsT/MiVNijZf5FJvpBoHm8ogw4s5z38tP/8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=R8Oc+fzjUzlgASDthcFLdNuCbHEwussxZkLz4SJmQIZyxqtTjr+qXLmTk3VICGivG4B1hPFNXY7CItZovl0yBhQ7LtEmxKvYRLPE+DEwaer5joWkjkw+i7Xqsdy2WQ2uR5S7lwnEHTi4vkc/rIsgXwimcxxsr9eEgyiKQaqS5E4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=M+vQuAxW; 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="M+vQuAxW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 574001F0089B; Wed, 30 Sep 2026 17:27:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790789263; bh=aA3Z8wbfZ8AW9nEuRpVR26q3eENpi14OItXmuk4hFTM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=M+vQuAxW6nOxT3yYjl0VkHxuLuxoQWxYGev6GiYNVyycr79FiKTQsqD3mQ8PLuDPL 8+UVyd8TH/NEvfGlFyOioZ5WovLrJTGerOyuZfeBAezGy7KZiJo39N8B596DRTY3TU CD6BdnfeUpZpIE1bqyICXSFRQ6j5aL+v2It0iuMw= 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 6.12 417/877] net: skbuff: fix pull-bound underflow in skb_checksum_setup_ipv6() Date: Wed, 30 Sep 2026 17:22:08 +0200 Message-ID: <20260930152423.690856706@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152414.738996857@linuxfoundation.org> References: <20260930152414.738996857@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 6.12-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 1e4f7b8e952cc..623d9d10a208f 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5841,7 +5841,8 @@ 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; @@ -5856,7 +5857,8 @@ 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; @@ -5871,7 +5873,8 @@ 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