From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 690 invoked by alias); 16 Jan 2013 22:40:45 -0000 Received: (qmail 31344 invoked by uid 48); 16 Jan 2013 22:40:22 -0000 From: "macro@linux-mips.org" To: glibc-bugs@sourceware.org Subject: [Bug dynamic-link/15022] New: Global-scope dlopen issues in static executables Date: Wed, 16 Jan 2013 22:40:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: glibc X-Bugzilla-Component: dynamic-link X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: macro@linux-mips.org X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Message-ID: X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 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 X-SW-Source: 2013-01/txt/msg00121.txt.bz2 http://sourceware.org/bugzilla/show_bug.cgi?id=15022 Bug #: 15022 Summary: Global-scope dlopen issues in static executables Product: glibc Version: unspecified Status: NEW Severity: normal Priority: P2 Component: dynamic-link AssignedTo: unassigned@sourceware.org ReportedBy: macro@linux-mips.org Classification: Unclassified We have two issues with dlopen [1] issued from static executables when the global scope is accessed. First, an attempt to add a dynamic shared module to the global scope (i.e. with RTLD_GLOBAL requested) crashes like this: Program received signal SIGSEGV, Segmentation fault. add_to_global (new=0x49ef60) at dl-open.c:101 101 ns->_ns_global_scope_alloc This is because at this point in static executables no global search list data structure has been initialised and as result the _ns_main_searchlist member of _dl_ns[LM_ID_BASE] (the initial namespace) is null. Second, an attempt to access the global scope itself (i.e. by using a null file name pointer) fails with an obscure error like: /path/to/dir/: cannot read file data: Is a directory (that can be retrieved with dlerror), where /path/to/dir/ is the first directory searched according to the dynamic load engine's shared module lookup policy. This is because the null file name pointer is internally converted to an empty string, that is in turn looked for and then opened in the directories examined. Of course that succeeds -- the directory itself is opened, but then the engine gets confused by the outcome and bails out. The use of an empty string works in dynamic executables, because for them the dynamic loader has already prepared a link map referring to a file whose name is empty -- which, by means of how that code works, is the executable itself -- and that makes the loader abandon any file look-ups and use the link map already present. The two issues both boil down to the same bug -- no global scope present. Patch offered: http://sourceware.org/ml/libc-alpha/2013-01/msg00635.html [1] http://pubs.opengroup.org/onlinepubs/7908799/xsh/dlopen.html -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.