From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 25660 invoked by alias); 5 Oct 2013 11:29:56 -0000 Mailing-List: contact glibc-bugs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: glibc-bugs-owner@sourceware.org Received: (qmail 25614 invoked by uid 48); 5 Oct 2013 11:29:52 -0000 From: "slyfox at inbox dot ru" To: glibc-bugs@sourceware.org Subject: [Bug libc/16004] New: memcpy/strcpy: detect memory overlap and crash when error is detected Date: Sat, 05 Oct 2013 11:29:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: glibc X-Bugzilla-Component: libc X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: enhancement X-Bugzilla-Who: slyfox at inbox dot ru X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status bug_severity priority component assigned_to reporter cc Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2013-10/txt/msg00042.txt.bz2 https://sourceware.org/bugzilla/show_bug.cgi?id=16004 Bug ID: 16004 Summary: memcpy/strcpy: detect memory overlap and crash when error is detected Product: glibc Version: unspecified Status: NEW Severity: enhancement Priority: P2 Component: libc Assignee: unassigned at sourceware dot org Reporter: slyfox at inbox dot ru CC: drepper.fsp at gmail dot com Recently amount of bugs regarding to memcpy() copy ordering grown. I guess it's due to new memcpy@GLIBC_2.14 on new CPUs. What scary is bugs are always data corruptions and almost never immediate application crashes (usually seen way later, that in actual memcpy call). Thus they live very long time unnoticed. Sometimes bug exhibits only on a subset of hardware (on core i7, but not core2, same libc) or even oncertain heap. I guess it's due to different semantics of memcpy IFUNC implelentations on different host CPUs (depend on linear address alignment). I'd like to ask to put memory overlap checking right into: - memcpy implementations themselves before calling assembly implementation - if above is too heavyweight, then do it only in _FORTIFY_SOURCE mode - if above is too heavyweight, then add some variable/knob to allow putting slow checky memcpy at IFUNC startup time. Same goes for strcpy. Sometimes people do silly things, like strcpy (some_str, some_str + strlen ("pref")); and get data corruption. Thank you! Some data corruptions I've found myself: https://bugs.gentoo.org/show_bug.cgi?id=486984 - aircrack-ng's packet parsers bug with memcpy to move packes for some bytes. https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3387206f26e1b48703e810175b98611a4fd8e8ea - filesystem corruption bug. It's a kernel patch, but usermode linux can be forced to use libc's memcpy to find such bugs easier. https://github.com/MidnightCommander/mc/commit/e48cb7c89ff3e54de70130a3de2136a9902a023d - occasional data corruption of final filepaths -- You are receiving this mail because: You are on the CC list for the bug.