From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <30VKHYgcKCq4aOgYfOmUccUZS.QcaZWPQ-OZdVOgcifQSkOfS.cfU@flex--maskray.bounces.google.com> Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by sourceware.org (Postfix) with ESMTPS id 7C3063857345 for ; Fri, 20 May 2022 08:35:30 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 7C3063857345 Received: by mail-yb1-xb4a.google.com with SMTP id y17-20020a258611000000b0064dd2e4eeb5so6542971ybk.7 for ; Fri, 20 May 2022 01:35:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=HspaG966Z6a8eEobpfZYkbGSz8QxTi6k1ak0OAgow/U=; b=RTA9Agxw0Bp5HdxjIPuzOa8PQQmTTr3ilXMx/ybmqBCafiHK18WfVV8TgfNRKWjJkv kESlDp1JndnFjHGETQbdQKcBROnzULBx4g4J6kR5JOflWIBNCjEG00K+AzdVMnL/IGb5 U7YshUVQ1duXDBEJd3IT+9H6DYk/TBOAhv2uJcasa10x2njjTTjAgdqYBWuuYM8C66zQ RnEFnrw7NoGbjBu6fTFPJUxS3fMuFBEq2uLTHXbTUKxi8+AQYctXuBdTDgiq9pQTukO9 ayaHk/xBTSWkxdr/wsTUnLu1+cMw//CnDyk4B5ZJexrQcZOJVSQmukJvQPuAvPZ+rpFR U1ig== X-Gm-Message-State: AOAM532wob/clgWpNCiH1v4Cftn7cdWr+D7iMrZQpoGHtqQ1lF/vshc6 1iBS9jSHgw0iHBx5bJ7OMGITXYBpfE+tLyoNdYnwr6FzPo6mBdZXd2bvg8h5XH+9LSkcrQQ8Wkv s9TwtH/9pf23LtA44rJui8UIvXOQboLSj9poofsz9EXrDG6Cj08b+EnguAKTa0u+aPmVq X-Google-Smtp-Source: ABdhPJyRUZZ2RXu/mFkLLtItYSRfG/kw7Muajl69MRQQbIuSByMLw058QU/wOdvdnCoqzlz+TU3/6onhaNu+ X-Received: from maskray1.svl.corp.google.com ([2620:15c:2ce:200:1097:e502:cc01:668c]) (user=maskray job=sendgmr) by 2002:a25:33d6:0:b0:64a:9d22:f005 with SMTP id z205-20020a2533d6000000b0064a9d22f005mr8241265ybz.54.1653035729797; Fri, 20 May 2022 01:35:29 -0700 (PDT) Date: Fri, 20 May 2022 01:35:07 -0700 Message-Id: <20220520083507.2368165-1-maskray@google.com> Mime-Version: 1.0 Subject: [PATCH] dlsym: Make RTLD_NEXT prefer default version definition [#BZ #14932] From: Fangrui Song To: libc-alpha@sourceware.org, Florian Weimer Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-19.7 required=5.0 tests=BAYES_00, DKIMWL_WL_MED, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 20 May 2022 08:35:32 -0000 When the first object providing foo defines both foo@v1 and foo@@v2, dlsym(RTLD_NEXT, "foo") returns foo@v1 while dlsym(RTLD_DEFAULT, "foo") returns foo@@v2. The issue is that RTLD_DEFAULT use the DL_LOOKUP_RETURN_NEWEST flag while RTLD_NEXT doesn't. Fix the RTLD_NEXT branch to use DL_LOOKUP_RETURN_NEWEST. --- elf/Makefile | 7 +++++++ elf/dl-sym.c | 2 +- elf/nextmod3.c | 19 +++++++++++++++++++ elf/nextmod3.map | 3 +++ elf/tst-next-ver.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 76 insertions(+), 1 deletion(-) create mode 100644 elf/nextmod3.c create mode 100644 elf/nextmod3.map create mode 100644 elf/tst-next-ver.c diff --git a/elf/Makefile b/elf/Makefile index 6f4ea78007..6cc0023364 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -425,6 +425,7 @@ tests += \ tst-initorder2 \ tst-latepthread \ tst-main1 \ + tst-next-ver \ tst-nodelete2 \ tst-nodelete-dlclose \ tst-nodelete-opened \ @@ -711,6 +712,7 @@ modules-names += \ neededobj6 \ nextmod1 \ nextmod2 \ + nextmod3 \ nodel2mod1 \ nodel2mod2 \ nodel2mod3 \ @@ -1689,6 +1691,9 @@ $(objpfx)reldep4.out: $(objpfx)reldep4mod1.so $(objpfx)reldep4mod2.so $(objpfx)next: $(objpfx)nextmod1.so $(objpfx)nextmod2.so LDFLAGS-next = -Wl,--no-as-needed +$(objpfx)tst-next-ver: $(objpfx)nextmod3.so +LDFLAGS-tst-next-ver = -Wl,--no-as-needed + $(objpfx)unload2.out: $(objpfx)unload2mod.so $(objpfx)unload2dep.so $(objpfx)lateglobal.out: $(objpfx)ltglobmod1.so $(objpfx)ltglobmod2.so @@ -2436,6 +2441,8 @@ $(objpfx)tst-linkall-static: \ endif endif +LDFLAGS-nextmod3.so = -Wl,--version-script=nextmod3.map + # The application depends on the DSO, and the DSO loads the plugin. # The plugin also depends on the DSO. This creates the circular # dependency via dlopen that we're testing to make sure works. diff --git a/elf/dl-sym.c b/elf/dl-sym.c index aa993942df..b1cf42f36d 100644 --- a/elf/dl-sym.c +++ b/elf/dl-sym.c @@ -144,7 +144,7 @@ RTLD_NEXT used in code not dynamically loaded")); l = l->l_loader; result = GLRO(dl_lookup_symbol_x) (name, match, &ref, l->l_local_scope, - vers, 0, 0, match); + vers, 0, flags, match); } else { diff --git a/elf/nextmod3.c b/elf/nextmod3.c new file mode 100644 index 0000000000..96608a65c0 --- /dev/null +++ b/elf/nextmod3.c @@ -0,0 +1,19 @@ +int +foo_v1 (int a) +{ + return 1; +} +asm (".symver foo_v1, foo@v1"); + +int +foo_v2 (int a) +{ + return 2; +} +asm (".symver foo_v2, foo@v2"); + +int +foo (int a) +{ + return 3; +} diff --git a/elf/nextmod3.map b/elf/nextmod3.map new file mode 100644 index 0000000000..0a8e4e4ee3 --- /dev/null +++ b/elf/nextmod3.map @@ -0,0 +1,3 @@ +v1 { }; +v2 { }; +v3 { foo; }; diff --git a/elf/tst-next-ver.c b/elf/tst-next-ver.c new file mode 100644 index 0000000000..7241f9038b --- /dev/null +++ b/elf/tst-next-ver.c @@ -0,0 +1,46 @@ +/* Test RTLD_DEFAULT/RTLD_NEXT when the definition has multiple versions. + Copyright (C) 2018-2022 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include + +#include "testobj.h" + +static int +do_test (void) +{ + /* Resolve to foo@@v3 in nextmod3.so, instead of + foo@v1 or foo@v2. */ + int (*fp) (int) = dlsym (RTLD_DEFAULT, "foo"); + int res = fp (0); + printf ("preload (0) = %d, %s\n", res, res == 3 ? "ok" : "wrong"); + if (res != 3) + return 1; + + /* Resolve to foo@@v3 in nextmod3.so, instead of + foo@v1 or foo@v2. */ + fp = dlsym (RTLD_NEXT, "foo"); + res = fp (0); + printf ("preload (0) = %d, %s\n", res, res == 3 ? "ok" : "wrong"); + if (res != 3) + return 1; + + return 0; +} + +#include -- 2.36.1.124.g0e6072fb45-goog