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 65AFA34F24E; Wed, 30 Sep 2026 15:57:41 +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=1790783864; cv=none; b=Q97KL84AHg7uC8B0V6tH68adSbcxyatxkgIFjGmjXSpX7NDu0302C0gxQeN5TLdS6GY3i/Yo635gFQtWeRghJH+OH5i9/lBP9nFgQnlPab5uD4e0MUoKys4byodcPntEXWaDN4zi3A9njE3TzmcWwbYq2yMdtrX4FsQdIWY14TY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790783864; c=relaxed/simple; bh=UNnsW4du0A5CU/5uJ1/oiR1Kiyc7QLTsSOY6qvAFwUo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=egl4z7kIKHysftlNERDiHWi+WAnfKTAatt5v9gusQEBC/fXXJNw6K3xI/RS1oW0GIBvP5uB2pYqzQKPPz4syNv6SklXGc9i7/hzWRWm0fFAmdak5EA9qLHXBytrP0Ktu4fyAAL5QTL4OmFp3RBX+JftGZvtdqtfk2mFFNr6+2is= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=TO3f/D49; 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="TO3f/D49" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 926221F00899; Wed, 30 Sep 2026 15:57:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790783861; bh=HJQTLajTAgoVogpOj63Py/FqVjryi16Yro3k52PVI1I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=TO3f/D490Rj66bf5DFPIOjctK6Satmbx3rHgZKcTvvezy7i2pCD+5B9CtkXDIMh7Z Gt1dRACmlxgiJlvKcsGVQNAO7D1c+m419brMuxC+36uwqDDBHBIX2eyBFF2bhlpzE+ +g5ksD1XJcMm9xp3JQqMauMCv3VFWASaMO4HyQAo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?J=C3=A9r=C3=A9my=20Jean?= , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.10 503/595] net: gue: reject invalid REMCSUM offsets Date: Wed, 30 Sep 2026 17:26:36 +0200 Message-ID: <20260930152358.516880412@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152347.700140858@linuxfoundation.org> References: <20260930152347.700140858@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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jérémy Jean [ Upstream commit 2566866fc30965d915d0b52b5c3323b362619f0e ] The REMCSUM option carries an absolute checksum start and checksum field offset. gue_remcsum() passes them to skb_remcsum_process(), whose partial path stores offset - start in the u16 skb->csum_offset variable. If offset is less than start, this underflows. A forwarded packet can retain CHECKSUM_PARTIAL and reach a NETIF_F_HW_CSUM driver which trusts the metadata, leading skb_copy_and_csum_dev() to write two bytes about 64 KiB beyond the destination buffer. Reject reversed tuples in validate_gue_flags(), after the existing length validation, so all GUE parsers enforce the ordering in one place. Fixes: fe881ef11cf0 ("gue: Use checksum partial with remote checksum offload") Signed-off-by: Jérémy Jean Link: https://patch.msgid.link/20260915124806.2852293-2-Jeremy.Jean@oss.cyber.gouv.fr Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/gue.h | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/include/net/gue.h b/include/net/gue.h index e5246d5d3e87d..3d8a4e971ad99 100644 --- a/include/net/gue.h +++ b/include/net/gue.h @@ -81,8 +81,9 @@ static inline size_t guehdr_priv_flags_len(__be32 flags) } /* Validate standard and private flags. Returns non-zero (meaning invalid) - * if there is an unknown standard or private flags, or the options length for - * the flags exceeds the options length specific in hlen of the GUE header. + * if there is an unknown standard or private flags, if the options length for + * the flags exceeds the options length specified in hlen of the GUE header, or + * if a private option contains invalid data. */ static inline int validate_gue_flags(struct guehdr *guehdr, size_t optlen) { @@ -100,8 +101,8 @@ static inline int validate_gue_flags(struct guehdr *guehdr, size_t optlen) /* Private flags are last four bytes accounted in * guehdr_flags_len */ - __be32 pflags = *(__be32 *)((void *)&guehdr[1] + - len - GUE_LEN_PRIV); + void *data = (void *)&guehdr[1] + len; + __be32 pflags = *(__be32 *)(data - GUE_LEN_PRIV); if (pflags & ~GUE_PFLAGS_ALL) return 1; @@ -109,6 +110,16 @@ static inline int validate_gue_flags(struct guehdr *guehdr, size_t optlen) len += guehdr_priv_flags_len(pflags); if (len > optlen) return 1; + + if (pflags & GUE_PFLAG_REMCSUM) { + __be16 *pd = data; + + /* The field offset pd[1] must not be less + * than the start pd[0]. + */ + if (ntohs(pd[1]) < ntohs(pd[0])) + return 1; + } } return 0; -- 2.53.0