From patchwork Tue Apr 25 15:04:19 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 9698395 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 34161603F4 for ; Tue, 25 Apr 2017 15:04:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2BB8E28653 for ; Tue, 25 Apr 2017 15:04:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 208362865B; Tue, 25 Apr 2017 15:04:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 560D728657 for ; Tue, 25 Apr 2017 15:04:36 +0000 (UTC) Received: (qmail 8156 invoked by uid 550); 25 Apr 2017 15:04:35 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 8136 invoked from network); 25 Apr 2017 15:04:34 -0000 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=zx2c4.com; h=from:to:cc :subject:date:message-id:in-reply-to:references; s=mail; bh=0LjU f0DBBF8epOvx3MX83HCCBeo=; b=g4//YGNKPnblOBLvMIKxqVYm6eI1vU1sop1l 5dlhHGdKa4v5eNkWf8VtPvwqw/22WrKWrAbH8Puk9XURlTeVMmRlncEGtAxVdpo7 vaWgVUgYkKaopm9sotZtwhyzn2A/L42yocntg0FmUUo9JTr5hS1bBbuq7XOO6UiL K3hiMPVxRN0KF+d9xXcR9Egdki0nYcU+lNEoBJllC/EnURNmRBzpqRBY6qE7mdBI UUREdFWmk/N9SdNQX+JQ80KgLxnWXvvEY/sLRU7YCTDhcmQpv3Xr5ANtAwT1GutW caWvgQioY5JOvE9wA2zF1ZxW427HoFY2N0S3cQdr+1UhflwP1A== From: "Jason A. Donenfeld" To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, davem@davemloft.net, David.Laight@aculab.com, kernel-hardening@lists.openwall.com Cc: "Jason A. Donenfeld" Date: Tue, 25 Apr 2017 17:04:19 +0200 Message-Id: <20170425150419.2060-1-Jason@zx2c4.com> X-Mailer: git-send-email 2.12.2 In-Reply-To: <20170425.104731.631398016575024152.davem@davemloft.net> References: <20170425.104731.631398016575024152.davem@davemloft.net> Subject: [kernel-hardening] [PATCH v4 1/5] skbuff: return -EMSGSIZE in skb_to_sgvec to prevent overflow X-Virus-Scanned: ClamAV using ClamSMTP This is a defense-in-depth measure in response to bugs like 4d6fa57b4dab ("macsec: avoid heap overflow in skb_to_sgvec") Signed-off-by: Jason A. Donenfeld --- v4 fixes the commit message and moves the check into the inner-most if. net/core/skbuff.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index f86bf69cfb8d..e75640006d78 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3489,7 +3489,9 @@ void __init skb_init(void) * @len: Length of buffer space to be mapped * * Fill the specified scatter-gather list with mappings/pointers into a - * region of the buffer space attached to a socket buffer. + * region of the buffer space attached to a socket buffer. Returns either + * the number of scatterlist items used, or -EMSGSIZE if the contents + * could not fit. */ static int __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) @@ -3517,6 +3519,8 @@ __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]); if ((copy = end - offset) > 0) { skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; + if (elt && sg_is_last(&sg[elt - 1])) + return -EMSGSIZE; if (copy > len) copy = len; @@ -3537,6 +3541,9 @@ __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) end = start + frag_iter->len; if ((copy = end - offset) > 0) { + if (elt && sg_is_last(&sg[elt - 1])) + return -EMSGSIZE; + if (copy > len) copy = len; elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start, @@ -3581,6 +3588,9 @@ int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int le { int nsg = __skb_to_sgvec(skb, sg, offset, len); + if (nsg <= 0) + return nsg; + sg_mark_end(&sg[nsg - 1]); return nsg;