From patchwork Tue Feb 8 18:36:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella Netto X-Patchwork-Id: 50922 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 4D8C2385AC2E for ; Tue, 8 Feb 2022 18:37:06 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4D8C2385AC2E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1644345426; bh=sWENVztEXpwUycEx2rvKG4gmolPz6KDo2MM/5pZtId4=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=ryoIbMlaODjv4DLkHgeVSmiYBPTTjBIhLUpX2ltuDaviCmUClR34NWI9Wp89P8ukN MqVfJ6o++wkswGLkD2a+rbJFpNagbSI/3kRdmmQT4GwUc68rr/m9URh7IkKnjo5UzD 9fnxUd9Kb98zms4q2oo1n0TJZaD5ltoYW0d5KJjk= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-oi1-x229.google.com (mail-oi1-x229.google.com [IPv6:2607:f8b0:4864:20::229]) by sourceware.org (Postfix) with ESMTPS id 9008F3857C4F for ; Tue, 8 Feb 2022 18:36:44 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 9008F3857C4F Received: by mail-oi1-x229.google.com with SMTP id r27so21527337oiw.4 for ; Tue, 08 Feb 2022 10:36:44 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=sWENVztEXpwUycEx2rvKG4gmolPz6KDo2MM/5pZtId4=; b=UpAqCP+FDrqsMi6hDy2wtRwOJCBEQzIFn6+hZkhrLxJ7Keo0U3AR4WYBJuc5SL8tIQ 2E3PmTdLah848Bpg/yEuJ/Jzz4tkCEUcHjEDwcNTh9NdwxMUwlIBLg+R1AKpnGOjbbDS ynfPmTAphhfnqzUL4AsL9sOboOqHXlF1MQGagoAtd9bPLaX9dxrKNkU/N/ay8BzFc1sQ 6GzeDjVl6vOAuXZzyJS9prOCXG4s208mIUiiWbHvZlhHcNW0RRyJpusAGe+esJwKpxn/ aAEeNF7giQse+jcW5Z5gSsccqLOueB7xj/2pnWdTF60OAWppMfs3EYDfA62P7g9Qiyec 8nsQ== X-Gm-Message-State: AOAM5317EdITvDrxIWpg+hCjBlcZ952LmpkpLeBlPBUTN+cAz+q1IjYD uHGVOHL3pny1fBnW+gT46Tv0HpblAZ+llg== X-Google-Smtp-Source: ABdhPJwP4DIOg5A9zKKgHFMJZwD0/IU9axcPxTKsLaxme0KhjhZG/AEfEglG1TIKmIk4I8blFnXhcg== X-Received: by 2002:a05:6808:2182:: with SMTP id be2mr1172145oib.185.1644345403529; Tue, 08 Feb 2022 10:36:43 -0800 (PST) Received: from birita.. ([2804:431:c7ca:733:86a9:ad5:adef:2f3e]) by smtp.gmail.com with ESMTPSA id t31sm6181500oaa.9.2022.02.08.10.36.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Feb 2022 10:36:43 -0800 (PST) To: libc-alpha@sourceware.org Subject: [PATCH] elf: Fix DFS sorting algorithm for LD_TRACE_LOADED_OBJECTS with missing libraries (BZ #28868) Date: Tue, 8 Feb 2022 15:36:39 -0300 Message-Id: <20220208183639.2262680-1-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 X-Spam-Status: No, score=-12.9 required=5.0 tests=BAYES_00, 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 autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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: Adhemerval Zanella via Libc-alpha From: Adhemerval Zanella Netto Reply-To: Adhemerval Zanella Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" The _dl_map_object_deps ignores l_faked objects (set if the underlying file can't be opened by _dl_map_object): 490 for (nlist = 0, runp = known; runp; runp = runp->next) 491 { 492 if (__builtin_expect (trace_mode, 0) && runp->map->l_faked) 493 /* This can happen when we trace the loading. */ 494 --map->l_searchlist.r_nlist; 495 else 496 { 497 if (runp->map == map) 498 map_index = nlist; 499 map->l_searchlist.r_list[nlist++] = runp->map; 500 } 501 502 /* Now clear all the mark bits we set in the objects on the search list 503 to avoid duplicates, so the next call starts fresh. */ 504 runp->map->l_reserved = 0; 505 } If there any missing libraries being processed, they will not be considered on final nlist size passed on _dl_sort_maps later in the function. And it is then used on _dl_sort_maps_dfs on the stack allocated working maps: 222 /* Array to hold RPO sorting results, before we copy back to maps[]. */ 223 struct link_map *rpo[nmaps]; 224 225 /* The 'head' position during each DFS iteration. Note that we start at 226 one past the last element due to first-decrement-then-store (see the 227 bottom of above dfs_traversal() routine). */ 228 struct link_map **rpo_head = &rpo[nmaps]; However while transversing the 'l_initfini' on dfs_traversal it will still considere the l_faked maps and thus update rpo more times than the allocated working 'rpo', overflowing the stack object. As suggested in bugzilla, one option would be to avoid sorting the maps for trace mode. However I think ignoring l_faked object does make sense (there is one less constraint to call the sorting function), it allows a slight less stack usage for trace, and it is slight simpler solution. The tests does trigger the stack overflow, however I tried to make it more generic to check different scenarios or missing objects. Checked on x86_64-linux-gnu. --- elf/Makefile | 60 +++++++++++++++++++++++++++++++++ elf/dl-sort-maps.c | 2 +- elf/libtracemod1.c | 1 + elf/libtracemod2.c | 1 + elf/libtracemod3.c | 1 + elf/libtracemod4.c | 1 + elf/libtracemod5.c | 1 + elf/libtracemod6.c | 1 + elf/tst-trace1.exp | 4 +++ elf/tst-trace2.exp | 6 ++++ elf/tst-trace3.exp | 6 ++++ elf/tst-trace4.exp | 6 ++++ elf/tst-trace5.exp | 6 ++++ scripts/tst-ld-trace.py | 75 +++++++++++++++++++++++++++++++++++++++++ 14 files changed, 170 insertions(+), 1 deletion(-) create mode 100644 elf/libtracemod1.c create mode 100644 elf/libtracemod2.c create mode 100644 elf/libtracemod3.c create mode 100644 elf/libtracemod4.c create mode 100644 elf/libtracemod5.c create mode 100644 elf/libtracemod6.c create mode 100644 elf/tst-trace1.exp create mode 100644 elf/tst-trace2.exp create mode 100644 elf/tst-trace3.exp create mode 100644 elf/tst-trace4.exp create mode 100644 elf/tst-trace5.exp create mode 100755 scripts/tst-ld-trace.py diff --git a/elf/Makefile b/elf/Makefile index ac37159b89..fefc000f80 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -819,6 +819,11 @@ modules-names = \ tst-tlsmod8 \ tst-tlsmod9 \ tst-unique1mod1 \ + libtracemod1 \ + libtracemod2 \ + libtracemod3 \ + libtracemod4 \ + libtracemod5 \ tst-unique1mod2 \ tst-unique2mod1 \ tst-unique2mod2 \ @@ -1072,6 +1077,8 @@ tests-special += \ $(objpfx)tst-initorder2-cmp.out \ $(objpfx)tst-unused-dep-cmp.out \ $(objpfx)tst-unused-dep.out \ + $(objpfx)tst-trace1.out \ + $(objpfx)tst-trace2.out \ # tests-special endif @@ -2733,3 +2740,56 @@ $(objpfx)tst-p_align3: $(objpfx)tst-p_alignmod3.so $(objpfx)tst-p_align3.out: tst-p_align3.sh $(objpfx)tst-p_align3 $(SHELL) $< $(common-objpfx) '$(test-program-prefix)'; \ $(evaluate-test) + + +libtracemod-suffixes = 5 4 3 2 1 +define libtracemod +$(objpfx)libtracemod$(1).stamp: $(objpfx)libtracemod$(1).so + touch $(objpfx)libtracemod$(1).stamp +endef +$(foreach s,$(libtracemod-suffixes), $(eval $(call libtracemod,$(s)))) + +# Move the library to a folder so it can be selected by --library-path +define libtracemod-mv + test -d $(objpfx)libtracemod$(1) || mkdir $(objpfx)libtracemod$(1) + test -f $(objpfx)libtracemod$(1).so \ + && mv $(objpfx)libtracemod$(1).so $(objpfx)libtracemod$(1) +endef +libtracemod-mv: $(objpfx)libtracemod1.stamp + $(call libtracemod-mv,2) + $(call libtracemod-mv,3) + $(call libtracemod-mv,4) + $(call libtracemod-mv,5) + +LDFLAGS-libtracemod1.so = -Wl,--no-as-needed \ + -L$(objpfx) -ltracemod2 -ltracemod3 +LDFLAGS-libtracemod2.so = -Wl,--no-as-needed \ + -L$(objpfx) -ltracemod4 -ltracemod5 +$(objpfx)libtracemod2.so: $(objpfx)libtracemod4.stamp \ + $(objpfx)libtracemod5.stamp +$(objpfx)libtracemod1.so: $(objpfx)libtracemod2.stamp \ + $(objpfx)libtracemod3.stamp + +define tst-trace-skeleton +$(objpfx)tst-trace$(1).out: $(..)scripts/tst-ld-trace.py \ + $(objpfx)libtracemod1.so \ + libtracemod-mv \ + tst-trace$(1).exp + ( $(test-wrapper-env) \ + LD_TRACE_LOADED_OBJECTS=1 \ + $(elf-objpfx)$(rtld-installed-name) \ + --library-path $(2) \ + $(objpfx)libtracemod1.so > $$@T \ + && $(PYTHON) $(..)scripts/tst-ld-trace.py $$@T tst-trace$(1).exp \ + ) > $$@; $$(evaluate-test) +endef + +$(eval $(call tst-trace-skeleton,1,.)) +$(eval $(call tst-trace-skeleton,2,\ + $(objpfx)libtracemod2)) +$(eval $(call tst-trace-skeleton,3,\ + $(objpfx)libtracemod2:$(objpfx)libtracemod3)) +$(eval $(call tst-trace-skeleton,4,\ + $(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4)) +$(eval $(call tst-trace-skeleton,5,\ + $(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4:$(objpfx)libtracemod5)) diff --git a/elf/dl-sort-maps.c b/elf/dl-sort-maps.c index 9e9d53ec47..f049178ac3 100644 --- a/elf/dl-sort-maps.c +++ b/elf/dl-sort-maps.c @@ -140,7 +140,7 @@ static void dfs_traversal (struct link_map ***rpo, struct link_map *map, bool *do_reldeps) { - if (map->l_visited) + if (map->l_visited || map->l_faked) return; map->l_visited = 1; diff --git a/elf/libtracemod1.c b/elf/libtracemod1.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod1.c @@ -0,0 +1 @@ +/* Empty */ diff --git a/elf/libtracemod2.c b/elf/libtracemod2.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod2.c @@ -0,0 +1 @@ +/* Empty */ diff --git a/elf/libtracemod3.c b/elf/libtracemod3.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod3.c @@ -0,0 +1 @@ +/* Empty */ diff --git a/elf/libtracemod4.c b/elf/libtracemod4.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod4.c @@ -0,0 +1 @@ +/* Empty */ diff --git a/elf/libtracemod5.c b/elf/libtracemod5.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod5.c @@ -0,0 +1 @@ +/* Empty */ diff --git a/elf/libtracemod6.c b/elf/libtracemod6.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod6.c @@ -0,0 +1 @@ +/* Empty */ diff --git a/elf/tst-trace1.exp b/elf/tst-trace1.exp new file mode 100644 index 0000000000..4a6f5211a6 --- /dev/null +++ b/elf/tst-trace1.exp @@ -0,0 +1,4 @@ +ld 1 +libc 1 +libtracemod2.so 0 +libtracemod3.so 0 diff --git a/elf/tst-trace2.exp b/elf/tst-trace2.exp new file mode 100644 index 0000000000..e13506e2eb --- /dev/null +++ b/elf/tst-trace2.exp @@ -0,0 +1,6 @@ +ld 1 +libc 1 +libtracemod2.so 1 +libtracemod3.so 0 +libtracemod4.so 0 +libtracemod5.so 0 diff --git a/elf/tst-trace3.exp b/elf/tst-trace3.exp new file mode 100644 index 0000000000..e574549d12 --- /dev/null +++ b/elf/tst-trace3.exp @@ -0,0 +1,6 @@ +ld 1 +libc 1 +libtracemod2.so 1 +libtracemod3.so 1 +libtracemod4.so 0 +libtracemod5.so 0 diff --git a/elf/tst-trace4.exp b/elf/tst-trace4.exp new file mode 100644 index 0000000000..31ca97b35b --- /dev/null +++ b/elf/tst-trace4.exp @@ -0,0 +1,6 @@ +ld 1 +libc 1 +libtracemod2.so 1 +libtracemod3.so 1 +libtracemod4.so 1 +libtracemod5.so 0 diff --git a/elf/tst-trace5.exp b/elf/tst-trace5.exp new file mode 100644 index 0000000000..5d7d953726 --- /dev/null +++ b/elf/tst-trace5.exp @@ -0,0 +1,6 @@ +ld 1 +libc 1 +libtracemod2.so 1 +libtracemod3.so 1 +libtracemod4.so 1 +libtracemod5.so 1 diff --git a/scripts/tst-ld-trace.py b/scripts/tst-ld-trace.py new file mode 100755 index 0000000000..8283e63cc6 --- /dev/null +++ b/scripts/tst-ld-trace.py @@ -0,0 +1,75 @@ +#!/usr/bin/python3 +# ELF editor for load align tests. +# Copyright (C) 2022 Free Software Foundation, Inc. +# Copyright The GNU Toolchain Authors. +# 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 +# . + +import argparse +import os +import sys + + +def is_vdso(lib): + return lib.startswith('linux-gate') or lib.startswith ('linux-vdso') + + +def parse_trace(fin, fref): + trace = [] + for line in fin: + line = line.strip() + if is_vdso(line): + continue + fields = line.split('=>' if '=>' in line else ' ') + lib = os.path.basename(fields[0].strip()) + if lib.startswith('ld-'): + lib = 'ld' + elif lib.startswith('libc'): + lib = 'libc' + found = 1 if fields[1].strip() != 'not found' else 0 + trace += ['{} {}'.format(lib, found)] + + reference = sorted(line.replace('\n','') for line in fref.readlines()) + + ret = 0 if sorted(trace) == reference else 1 + if ret != 0: + for i in reference: + if i not in trace: + print("Only in {}: {}".format(fref.name, i)) + for i in trace: + if i not in reference: + print("Only in {}: {}".format(fin.name, i)) + sys.exit (ret) + + +def get_parser(): + parser = argparse.ArgumentParser(description=__doc__) + parser.add_argument('input', + help='LD_TRACE_LOADED_OBJECTS input') + parser.add_argument('reference', + help='reference file to compare') + return parser + + +def main(argv): + parser = get_parser() + opts = parser.parse_args(argv) + with open(opts.input, 'r') as fin, open(opts.reference, 'r') as fref: + parse_trace(fin, fref) + + +if __name__ == '__main__': + main(sys.argv[1:])