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 0AA57521893; Wed, 30 Sep 2026 17:47:55 +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=1790790476; cv=none; b=FwvQoRxr17MkuJDDoj7CrMsFenQE2mb3xzdpaBA/i0useLp5rOlz9JkbOmnSs9pndt1UraMCUccvEfaIGP+6yZET0Fo6uTUwEkFhudKC/XuUFtkED97DnC9JlQdr70tyma4+MEu3Fcsoq4LgmFm+xsJA96Hmmq2E1o46f4x1ttc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790790476; c=relaxed/simple; bh=UFT9510Gje9M3l5vdABGr+vgDOucPA5JGVR/pooRkUw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=suXkx9UuJX20gacw5NtVGhRxwbObxYsGvSHcaIaM56QWiZUqa/H24NxEH6YbPYIm7W6I36QxavRQbHviL6FbAo6fEOkn59B7xEhxAluKz8UFCmz6MnElHVIYwhWOKkzyZicu3hbXZqSd6MIssAqeYjeP6dNo41g7JbTpauxKf1Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AuUxvQ2+; 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="AuUxvQ2+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69C501F000FF; Wed, 30 Sep 2026 17:47:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790790474; bh=F/uE20RJ0UY2xdUucfyRVngWiBzE9IomwiBYUg4owHU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AuUxvQ2+CRpUbFBb98Ityeu4cteTwKxHP1R9lffhTVw+7Qad3qkwrTaYfQN5NuXbV YSnlmQYwvuPBbOZsqGjYDXHImVyGmUwE41lwf7z3M2sc5+rQMIaC2bOIjAVxTN63CC M8u1Zcu4pmW1hrKgLnlZr/PZ6SFcKvoX27yLM1iY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vega , Yuqi Xu , Ren Wei , Simon Horman , Paolo Abeni , Sasha Levin Subject: [PATCH 6.12 843/877] net: ipconfig: bound DHCP option construction Date: Wed, 30 Sep 2026 17:29:14 +0200 Message-ID: <20260930152432.929483941@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: Yuqi Xu [ Upstream commit e47a1958e12abc3a17b5231a4f21c8f1bf662e08 ] ic_dhcp_init_options() appends the hostname (option 12), vendor-class (option 60) and client-ID (option 61) options into the fixed 312-byte bootp_pkt.exten[] buffer. Only the client-ID branch checked the remaining space; the hostname and vendor-class writes were unbounded. A 64-byte hostname together with the maximum 252-byte dhcpclass= identifier needs 18 + (2 + 64) + (2 + 252) = 338 of the 312 available bytes even before the terminating END marker, so the vendor-class memcpy runs past the end of exten[]. With CONFIG_FORTIFY_SOURCE this is reported as a field-spanning write and, when the kernel is booted with panic_on_warn=1, aborts boot with a panic. Route the optional options through a common helper that makes sure the option, its 2-byte header and the END marker all fit and drops an option that would not. Configurations with short options keep sending exactly the same bytes as before. Fixes: 130c0f47fdf9 ("ipconfig: send host-name in DHCP requests") Cc: stable@vger.kernel.org Reported-by: Vega Assisted-by: LLM Signed-off-by: Yuqi Xu Reviewed-by: Ren Wei Reviewed-by: Simon Horman Link: https://patch.msgid.link/7808dfbfa2162dfd0b19f59aff5742d6e0db2abb.1789798023.git.xuyuqiabc@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/ipv4/ipconfig.c | 45 ++++++++++++++++++++++++++------------------- 1 file changed, 26 insertions(+), 19 deletions(-) --- a/net/ipv4/ipconfig.c +++ b/net/ipv4/ipconfig.c @@ -676,6 +676,24 @@ static const u8 ic_bootp_cookie[4] = { 9 #ifdef IPCONFIG_DHCP +static bool __init +ic_dhcp_add_option(u8 **options, const u8 *end, u8 type, const void *value, + int len) +{ + u8 *e = *options; + + /* leave room for the option header and the END marker */ + if (len > U8_MAX || end - e < len + 3) + return false; + + *e++ = type; + *e++ = len; + memcpy(e, value, len); + *options = e + len; + + return true; +} + static void __init ic_dhcp_init_options(u8 *options, struct ic_device *d) { @@ -691,6 +709,7 @@ ic_dhcp_init_options(u8 *options, struct 42, /* NTP servers */ }; u8 mt = (ic_servaddr == NONE) ? DHCPDISCOVER : DHCPREQUEST; + u8 *end = options + sizeof(((struct bootp_pkt *)0)->exten); u8 *e = options; int len; @@ -721,31 +740,19 @@ ic_dhcp_init_options(u8 *options, struct e += sizeof(ic_req_params); if (ic_host_name_set) { - *e++ = 12; /* host-name */ len = strlen(utsname()->nodename); - *e++ = len; - memcpy(e, utsname()->nodename, len); - e += len; + ic_dhcp_add_option(&e, end, 12, utsname()->nodename, len); } if (*vendor_class_identifier) { - pr_info("DHCP: sending class identifier \"%s\"\n", - vendor_class_identifier); - *e++ = 60; /* Class-identifier */ len = strlen(vendor_class_identifier); - *e++ = len; - memcpy(e, vendor_class_identifier, len); - e += len; + if (ic_dhcp_add_option(&e, end, 60, vendor_class_identifier, len)) + pr_info("DHCP: sending class identifier \"%s\"\n", + vendor_class_identifier); } len = strlen(dhcp_client_identifier + 1); - /* the minimum length of identifier is 2, include 1 byte type, - * and can not be larger than the length of options - */ - if (len >= 1 && len < 312 - (e - options) - 1) { - *e++ = 61; - *e++ = len + 1; - memcpy(e, dhcp_client_identifier, len + 1); - e += len + 1; - } + /* the minimum length of identifier is 2, include 1 byte type */ + if (len >= 1) + ic_dhcp_add_option(&e, end, 61, dhcp_client_identifier, len + 1); *e++ = 255; /* End of the list */ }