From owner-freebsd-bugs@freebsd.org Sun Jan 24 03:05:55 2021 Return-Path: Delivered-To: freebsd-bugs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id C87924E8860 for ; Sun, 24 Jan 2021 03:05:55 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.nyi.freebsd.org (unknown [127.0.1.3]) by mx1.freebsd.org (Postfix) with ESMTP id 4DNdDM4xD2z3rKX for ; Sun, 24 Jan 2021 03:05:55 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id A952D4E8B43; Sun, 24 Jan 2021 03:05:55 +0000 (UTC) Delivered-To: bugs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id A914B4E8ADF for ; Sun, 24 Jan 2021 03:05:55 +0000 (UTC) (envelope-from bugzilla-noreply@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) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4DNdDM49txz3r48 for ; Sun, 24 Jan 2021 03:05:55 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 829111C74C for ; Sun, 24 Jan 2021 03:05:55 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id 10O35thu071055 for ; Sun, 24 Jan 2021 03:05:55 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from bugzilla@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 10O35tP8071054 for bugs@FreeBSD.org; Sun, 24 Jan 2021 03:05:55 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: bugzilla set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 252403] unsafe pointer arithmetic in regcomp() Date: Sun, 24 Jan 2021 03:05:55 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: bin X-Bugzilla-Version: Unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: commit-hook@FreeBSD.org X-Bugzilla-Status: In Progress X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: kevans@freebsd.org X-Bugzilla-Flags: mfc-stable12? mfc-stable11- X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 24 Jan 2021 03:05:55 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D252403 --- Comment #3 from commit-hook@FreeBSD.org --- A commit in branch stable/12 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=3D912086c27f9ab75253af8ae7914ae6001= 035a1b2 commit 912086c27f9ab75253af8ae7914ae6001035a1b2 Author: Miod Vallat AuthorDate: 2021-01-08 18:59:00 +0000 Commit: Kyle Evans CommitDate: 2021-01-24 03:04:58 +0000 libc: regex: rework unsafe pointer arithmetic regcomp.c uses the "start + count < end" idiom to check that there are "count" bytes available in an array of char "start" and "end" both point to. This is fine, unless "start + count" goes beyond the last element of the array. In this case, pedantic interpretation of the C standard makes the comparison of such a pointer against "end" undefined, and optimizers fr= om hell will happily remove as much code as possible because of this. An example of this occurs in regcomp.c's bothcases(), which defines bracket[3], sets "next" to "bracket" and "end" to "bracket + 2". Then it invokes p_bracket(), which starts with "if (p->next + 5 < p->end)"... Because bothcases() and p_bracket() are static functions in regcomp.c, there is a real risk of miscompilation if aggressive inlining happens. The following diff rewrites the "start + count < end" constructs into "= end - start > count". Assuming "end" and "start" are always pointing in the a= rray (such as "bracket[3]" above), "end - start" is well-defined and can be compared without trouble. As a bonus, MORE2() implies MORE() therefore SEETWO() can be simplified= a bit. PR: 252403 (cherry picked from commit d36b5dbe28d8ebab219fa29db533734d47f0c4a3) lib/libc/regex/regcomp.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) --=20 You are receiving this mail because: You are on the CC list for the bug.=