From owner-svn-src-all@freebsd.org Tue Mar 19 17:49:06 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id D7D4D152E287; Tue, 19 Mar 2019 17:49:05 +0000 (UTC) (envelope-from erj@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 78B5A8EC59; Tue, 19 Mar 2019 17:49:05 +0000 (UTC) (envelope-from erj@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 545A0CB70; Tue, 19 Mar 2019 17:49:04 +0000 (UTC) (envelope-from erj@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x2JHn4Mg064585; Tue, 19 Mar 2019 17:49:04 GMT (envelope-from erj@FreeBSD.org) Received: (from erj@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x2JHn4f8064584; Tue, 19 Mar 2019 17:49:04 GMT (envelope-from erj@FreeBSD.org) Message-Id: <201903191749.x2JHn4f8064584@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: erj set sender to erj@FreeBSD.org using -f From: Eric Joyner Date: Tue, 19 Mar 2019 17:49:04 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r345303 - head/sys/net X-SVN-Group: head X-SVN-Commit-Author: erj X-SVN-Commit-Paths: head/sys/net X-SVN-Commit-Revision: 345303 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 78B5A8EC59 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.96 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.998,0]; NEURAL_HAM_SHORT(-0.96)[-0.962,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US]; NEURAL_HAM_LONG(-1.00)[-1.000,0] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 Mar 2019 17:49:06 -0000 Author: erj Date: Tue Mar 19 17:49:03 2019 New Revision: 345303 URL: https://svnweb.freebsd.org/changeset/base/345303 Log: iflib: prevent possible infinite loop in iflib_encap From Jake: iflib_encap calls bus_dmamap_load_mbuf_sg. Upon it returning EFBIG, an m_collapse and an m_defrag are attempted to shrink the mbuf cluster to fit within the DMA segment limitations. However, if we call m_defrag, and then bus_dmamap_load_mbuf_sg returns EFBIG on the now defragmented mbuf, we will continuously re-call bus_dmamap_load_mbuf_sg over and over. This happens because m_head isn't NULL, and remap is >1, so we don't try to m_collapse or m_defrag again. The only way we exit the loop is if m_head is NULL. However, m_head can't be modified by the call to bus_dmamap_load_mbuf_sg, because we don't pass it as a double pointer. I believe this will be an incredibly rare occurrence, because it is unlikely that bus_dmamap_load_mbuf_sg will actually fail on the second defragment with an EFBIG error. However, it still seems like a possibility that we should account for. Fix the exit check to ensure that if remap is >1, we will also exit, even if m_head is not NULL. Submitted by: Jacob Keller Reviewed by: shurd@, gallatin@ MFC after: 1 week Sponsored by: Intel Corporation Differential Revision: https://reviews.freebsd.org/D19468 Modified: head/sys/net/iflib.c Modified: head/sys/net/iflib.c ============================================================================== --- head/sys/net/iflib.c Tue Mar 19 17:38:54 2019 (r345302) +++ head/sys/net/iflib.c Tue Mar 19 17:49:03 2019 (r345303) @@ -3276,9 +3276,14 @@ defrag: txq->ift_mbuf_defrag++; m_head = m_defrag(*m_headp, M_NOWAIT); } - remap++; - if (__predict_false(m_head == NULL)) + /* + * remap should never be >1 unless bus_dmamap_load_mbuf_sg + * failed to map an mbuf that was run through m_defrag + */ + MPASS(remap <= 1); + if (__predict_false(m_head == NULL || remap > 1)) goto defrag_failed; + remap++; *m_headp = m_head; goto retry; break;