From patchwork Fri May 27 11:15:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 54459 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 2B283395B44C for ; Fri, 27 May 2022 13:21:31 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 2B283395B44C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1653657691; bh=qQw6s7IBijnR0/CfuHjR/56CG5tgJixELB+DW63jVfk=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=MDJsQnqPGNsNt7tX6wNE/KuqECIP7udIayIxT5wjTXq+4CwgPm5i0niXpp1z1oUbB Gv6Bj/V24dXezO5xhTrEQ34GNWgQCoTRBu2Z7qRcy4bqHlK6pIfTJRrPInvq5AiUSA fuDsg8rRjTxpq0tC+PrIMSHrGj1bFFimcmKCQviQ= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 8D6A9395C05B for ; Fri, 27 May 2022 11:15:58 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 8D6A9395C05B Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-282-r3IbSHIHP9Cy41dzxMXjPw-1; Fri, 27 May 2022 07:15:55 -0400 X-MC-Unique: r3IbSHIHP9Cy41dzxMXjPw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 04AFB3AF42AA for ; Fri, 27 May 2022 11:15:55 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.71]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 30E501121315 for ; Fri, 27 May 2022 11:15:54 +0000 (UTC) To: libc-alpha@sourceware.org Subject: [PATCH] elf: Fix handling of symbol versions which hash to zero (bug 29190) Date: Fri, 27 May 2022 13:15:52 +0200 Message-ID: <87fskvfcpj.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-10.6 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE, URIBL_BLACK 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-Patchwork-Original-From: Florian Weimer via Libc-alpha From: Florian Weimer Reply-To: Florian Weimer Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" This was found through code inspection. No application impact is known. Reviewed-by: Fangrui Song --- elf/Makefile | 26 +++++++++++++++++ elf/dl-lookup.c | 22 ++++++++++---- elf/dl-version.c | 7 +++++ elf/tst-version-hash-zero-linkmod.c | 22 ++++++++++++++ elf/tst-version-hash-zero-linkmod.map | 7 +++++ elf/tst-version-hash-zero-mod.c | 20 +++++++++++++ elf/tst-version-hash-zero-mod.map | 13 +++++++++ elf/tst-version-hash-zero-refmod.c | 23 +++++++++++++++ elf/tst-version-hash-zero.c | 55 +++++++++++++++++++++++++++++++++++ 9 files changed, 189 insertions(+), 6 deletions(-) diff --git a/elf/Makefile b/elf/Makefile index 838fe39afb..f141eedfb0 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -466,6 +466,7 @@ tests += \ tst-unique2 \ tst-unwind-ctor \ tst-unwind-main \ + tst-version-hash-zero \ unload3 \ unload4 \ unload5 \ @@ -913,6 +914,9 @@ modules-names += \ tst-unique2mod1 \ tst-unique2mod2 \ tst-unwind-ctor-lib \ + tst-version-hash-zero-linkmod \ + tst-version-hash-zero-mod \ + tst-version-hash-zero-refmod \ unload2dep \ unload2mod \ unload3mod1 \ @@ -2960,3 +2964,25 @@ $(objpfx)tst-tls-allocation-failure-static-patched.out: \ grep -q '^Fatal glibc error: Cannot allocate TLS block$$' $@ \ && grep -q '^status: 127$$' $@; \ $(evaluate-test) + +$(objpfx)tst-version-hash-zero.out: \ + $(objpfx)tst-version-hash-zero-mod.so \ + $(objpfx)tst-version-hash-zero-refmod.so +$(objpfx)tst-version-hash-zero-mod.so: $(objpfx)tst-version-hash-zero-mod.os \ + tst-version-hash-zero-mod.map + $(LINK.o) -shared -o $@ $(LDFLAGS.so) $< \ + -Wl,--version-script=tst-version-hash-zero-mod.map +# The run-time test module tst-version-hash-zero-refmod.so is linked +# to a stub module, tst-version-hash-zero-linkmod.so, to produce an +# expected relocation error. +$(objpfx)tst-version-hash-zero-refmod.so: \ + $(objpfx)tst-version-hash-zero-linkmod.so +$(objpfx)tst-version-hash-zero-linkmod.so:\ + $(objpfx)tst-version-hash-zero-linkmod.os \ + tst-version-hash-zero-linkmod.map + $(LINK.o) -shared -o $@ $(LDFLAGS.so) $< \ + -Wl,--version-script=tst-version-hash-zero-linkmod.map \ + -Wl,--soname=tst-version-hash-zero-mod.so +$(objpfx)tst-version-hash-zero-refmod.so: \ + $(objpfx)tst-version-hash-zero-linkmod.so +tst-version-hash-zero-refmod.so-no-z-defs = yes diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c index a42f6d5390..9abe96fd92 100644 --- a/elf/dl-lookup.c +++ b/elf/dl-lookup.c @@ -114,12 +114,22 @@ check_match (const char *const undef_name, /* We can match the version information or use the default one if it is not hidden. */ ElfW(Half) ndx = verstab[symidx] & 0x7fff; - if ((map->l_versions[ndx].hash != version->hash - || strcmp (map->l_versions[ndx].name, version->name)) - && (version->hidden || map->l_versions[ndx].hash - || (verstab[symidx] & 0x8000))) - /* It's not the version we want. */ - return NULL; + if (map->l_versions[ndx].hash == version->hash + && strcmp (map->l_versions[ndx].name, version->name) == 0) + /* This is an exact version match. Return the symbol below. */ + ; + else + { + if (!version->hidden + && map->l_versions[ndx].name[0] == '\0' + && (verstab[symidx] & 0x8000) == 0 + && (*num_versions)++ == 0) + /* This is the global default version. Store it as a + fallback match. */ + *versioned_sym = sym; + + return NULL; + } } } else diff --git a/elf/dl-version.c b/elf/dl-version.c index cda0889209..c10ead82fe 100644 --- a/elf/dl-version.c +++ b/elf/dl-version.c @@ -357,6 +357,13 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode) ent = (ElfW(Verdef) *) ((char *) ent + ent->vd_next); } } + + /* The empty string has ELF hash zero. This avoids a NULL check + before the version string comparison in check_match in + dl-lookup.c. */ + for (unsigned int i = 0; i < map->l_nversions; ++i) + if (map->l_versions[i].name == NULL) + map->l_versions[i].name = ""; } /* When there is a DT_VERNEED entry with libc.so on DT_NEEDED, issue diff --git a/elf/tst-version-hash-zero-linkmod.c b/elf/tst-version-hash-zero-linkmod.c new file mode 100644 index 0000000000..f71574bd2d --- /dev/null +++ b/elf/tst-version-hash-zero-linkmod.c @@ -0,0 +1,22 @@ +/* Stub module for linking tst-version-hash-zero-refmod.so. + Copyright (C) 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; see the file COPYING.LIB. If + not, see . */ + +/* The version script assigns a different symbol version for the stub + module. Loading the module with the incorrect version is expected + to fail. */ +#include "tst-version-hash-zero-mod.c" diff --git a/elf/tst-version-hash-zero-linkmod.map b/elf/tst-version-hash-zero-linkmod.map new file mode 100644 index 0000000000..2dba7c22d7 --- /dev/null +++ b/elf/tst-version-hash-zero-linkmod.map @@ -0,0 +1,7 @@ +Base { + local: *; +}; + +OTHER_VERSION { + global: global_variable; +} Base; diff --git a/elf/tst-version-hash-zero-mod.c b/elf/tst-version-hash-zero-mod.c new file mode 100644 index 0000000000..f99c020746 --- /dev/null +++ b/elf/tst-version-hash-zero-mod.c @@ -0,0 +1,20 @@ +/* Test module with a zero version symbol hash. + Copyright (C) 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; see the file COPYING.LIB. If + not, see . */ + +/* The symbol version is assigned by version script. */ +int global_variable; diff --git a/elf/tst-version-hash-zero-mod.map b/elf/tst-version-hash-zero-mod.map new file mode 100644 index 0000000000..41eaff7914 --- /dev/null +++ b/elf/tst-version-hash-zero-mod.map @@ -0,0 +1,13 @@ +Base { + local: *; +}; + +/* Define the version so that tst-version-hash-zero-refmod.so passes + the initial symbol version check. */ +OTHER_VERSION { +} Base; + +/* This version string hashes to zero. */ +PPPPPPPPPPPP { + global: global_variable; +} Base; diff --git a/elf/tst-version-hash-zero-refmod.c b/elf/tst-version-hash-zero-refmod.c new file mode 100644 index 0000000000..29a9caaa40 --- /dev/null +++ b/elf/tst-version-hash-zero-refmod.c @@ -0,0 +1,23 @@ +/* Test module that triggers a relocation failure in tst-version-hash-zero. + Copyright (C) 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; see the file COPYING.LIB. If + not, see . */ + +/* This is bound to global_variable@@OTHER_VERSION via + tst-version-hash-zero-linkmod.so, but at run time, only + global_variable@PPPPPPPPPPPP exists. */ +extern int global_variable; +int *pointer_variable = &global_variable; diff --git a/elf/tst-version-hash-zero.c b/elf/tst-version-hash-zero.c new file mode 100644 index 0000000000..ad391bf202 --- /dev/null +++ b/elf/tst-version-hash-zero.c @@ -0,0 +1,55 @@ +/* Symbols with version hash zero should not match any version (bug 29190). + Copyright (C) 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; see the file COPYING.LIB. If + not, see . */ + +#include +#include +#include +#include + +static int +do_test (void) +{ + void *handle = xdlopen ("tst-version-hash-zero-mod.so", RTLD_NOW); + + /* This used to crash because some struct r_found_version entries + with hash zero did not have valid version strings. */ + TEST_VERIFY (xdlvsym (handle, "global_variable", "PPPPPPPPPPPP") != NULL); + + /* Consistency check. */ + TEST_VERIFY (xdlsym (handle, "global_variable") + == xdlvsym (handle, "global_variable", "PPPPPPPPPPPP")); + + /* This symbol version is supposed to be missing. */ + TEST_VERIFY (dlvsym (handle, "global_variable", "OTHER_VERSION") == NULL); + + /* tst-version-hash-zero-refmod.so references + global_variable@@OTHER_VERSION and is expected to fail to load. + dlvsym sets the hidden flag during lookup. Relocation does not, + so this exercises a different failure case. */ + TEST_VERIFY (dlopen ("tst-version-hash-zero-refmod.so", RTLD_NOW) == NULL); + const char *message = dlerror (); + if (strstr (message, + ": undefined symbol: global_variable, version OTHER_VERSION") + == NULL) + FAIL_EXIT1 ("unexpected dlopen failure: %s", message); + + xdlclose (handle); + return 0; +} + +#include