From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1791) id DDE23385842B; Wed, 27 Apr 2022 17:15:57 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org DDE23385842B Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Adhemerval Zanella To: glibc-cvs@sourceware.org Subject: [glibc/release/2.35/master] elf: Fix DFS sorting algorithm for LD_TRACE_LOADED_OBJECTS with missing libraries (BZ #28868) X-Act-Checkin: glibc X-Git-Author: Adhemerval Zanella X-Git-Refname: refs/heads/release/2.35/master X-Git-Oldrev: cb4d670d8f0f6ef4725094ea18a62729d852ce67 X-Git-Newrev: 10fe3cd309b32c003a6b98e08928e7d6007caecf Message-Id: <20220427171557.DDE23385842B@sourceware.org> Date: Wed, 27 Apr 2022 17:15:57 +0000 (GMT) X-BeenThere: glibc-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 27 Apr 2022 17:15:58 -0000 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=10fe3cd309b32c003a6b98e08928e7d6007caecf commit 10fe3cd309b32c003a6b98e08928e7d6007caecf Author: Adhemerval Zanella Date: Tue Feb 8 15:22:49 2022 -0300 elf: Fix DFS sorting algorithm for LD_TRACE_LOADED_OBJECTS with missing libraries (BZ #28868) On _dl_map_object the underlying file is not opened in trace mode (in other cases where the underlying file can't be opened, _dl_map_object quits with an error). 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 by _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 consider 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. Reviewed-by: Siddhesh Poyarekar (cherry picked from commit 3a0588ae48fb35384a6bd33f9b66403badfa1262) Diff: --- NEWS | 2 + elf/Makefile | 54 ++++++++++++++++++++++++ elf/dl-deps.c | 2 + elf/dl-sort-maps.c | 4 +- elf/libtracemod1-1.c | 1 + elf/libtracemod2-1.c | 1 + elf/libtracemod3-1.c | 1 + elf/libtracemod4-1.c | 1 + elf/libtracemod5-1.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 | 108 ++++++++++++++++++++++++++++++++++++++++++++++++ 15 files changed, 202 insertions(+), 1 deletion(-) diff --git a/NEWS b/NEWS index 2bfadde72d..87224df4c7 100644 --- a/NEWS +++ b/NEWS @@ -19,6 +19,8 @@ The following bugs are resolved with this release: __convert_scm_timestamps [28865] linux: _SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN are inaccurate without /sys and /proc + [28868] dynamic-link: Dynamic loader DFS algorithm segfaults on + missing libraries [28896] strncmp-avx2-rtm and wcsncmp-avx2-rtm fallback on non-rtm variants when avoiding overflow [28953] nss: Protect against errno changes in function lookup diff --git a/elf/Makefile b/elf/Makefile index 4bca0424a3..fa1ea28b25 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -652,6 +652,11 @@ modules-names = \ libmarkermod5-3 \ libmarkermod5-4 \ libmarkermod5-5 \ + libtracemod1-1 \ + libtracemod2-1 \ + libtracemod3-1 \ + libtracemod4-1 \ + libtracemod5-1 \ ltglobmod1 \ ltglobmod2 \ neededobj1 \ @@ -1112,6 +1117,11 @@ 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 \ + $(objpfx)tst-trace3.out \ + $(objpfx)tst-trace4.out \ + $(objpfx)tst-trace5.out \ # tests-special endif @@ -2787,3 +2797,47 @@ $(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)'; \ $(evaluate-test) + +LDFLAGS-libtracemod1-1.so += -Wl,-soname,libtracemod1.so +LDFLAGS-libtracemod2-1.so += -Wl,-soname,libtracemod2.so +LDFLAGS-libtracemod3-1.so += -Wl,-soname,libtracemod3.so +LDFLAGS-libtracemod4-1.so += -Wl,-soname,libtracemod4.so +LDFLAGS-libtracemod5-1.so += -Wl,-soname,libtracemod5.so + +$(objpfx)libtracemod1-1.so: $(objpfx)libtracemod2-1.so \ + $(objpfx)libtracemod3-1.so +$(objpfx)libtracemod2-1.so: $(objpfx)libtracemod4-1.so \ + $(objpfx)libtracemod5-1.so + +define libtracemod-x +$(objpfx)libtracemod$(1)/libtracemod$(1).so: $(objpfx)libtracemod$(1)-1.so + $$(make-target-directory) + cp $$< $$@ +endef +libtracemod-suffixes = 1 2 3 4 5 +$(foreach i,$(libtracemod-suffixes), $(eval $(call libtracemod-x,$(i)))) + +define tst-trace-skeleton +$(objpfx)tst-trace$(1).out: $(objpfx)libtracemod1/libtracemod1.so \ + $(objpfx)libtracemod2/libtracemod2.so \ + $(objpfx)libtracemod3/libtracemod3.so \ + $(objpfx)libtracemod4/libtracemod4.so \ + $(objpfx)libtracemod5/libtracemod5.so \ + $(..)scripts/tst-ld-trace.py \ + tst-trace$(1).exp + ${ $(PYTHON) $(..)scripts/tst-ld-trace.py \ + "$(test-wrapper-env) $(elf-objpfx)$(rtld-installed-name) \ + --library-path $(common-objpfx):$(strip $(2)) \ + $(objpfx)libtracemod1/libtracemod1.so" tst-trace$(1).exp \ + } > $$@; $$(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-deps.c b/elf/dl-deps.c index c8bab5cad5..cfe7f0743a 100644 --- a/elf/dl-deps.c +++ b/elf/dl-deps.c @@ -489,6 +489,8 @@ _dl_map_object_deps (struct link_map *map, for (nlist = 0, runp = known; runp; runp = runp->next) { + /* _dl_sort_maps ignores l_faked object, so it is safe to not consider + them for nlist. */ if (__builtin_expect (trace_mode, 0) && runp->map->l_faked) /* This can happen when we trace the loading. */ --map->l_searchlist.r_nlist; diff --git a/elf/dl-sort-maps.c b/elf/dl-sort-maps.c index 9e9d53ec47..96638d7ed1 100644 --- a/elf/dl-sort-maps.c +++ b/elf/dl-sort-maps.c @@ -140,7 +140,9 @@ static void dfs_traversal (struct link_map ***rpo, struct link_map *map, bool *do_reldeps) { - if (map->l_visited) + /* _dl_map_object_deps ignores l_faked objects when calculating the + number of maps before calling _dl_sort_maps, ignore them as well. */ + if (map->l_visited || map->l_faked) return; map->l_visited = 1; diff --git a/elf/libtracemod1-1.c b/elf/libtracemod1-1.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod1-1.c @@ -0,0 +1 @@ +/* Empty */ diff --git a/elf/libtracemod2-1.c b/elf/libtracemod2-1.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod2-1.c @@ -0,0 +1 @@ +/* Empty */ diff --git a/elf/libtracemod3-1.c b/elf/libtracemod3-1.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod3-1.c @@ -0,0 +1 @@ +/* Empty */ diff --git a/elf/libtracemod4-1.c b/elf/libtracemod4-1.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod4-1.c @@ -0,0 +1 @@ +/* Empty */ diff --git a/elf/libtracemod5-1.c b/elf/libtracemod5-1.c new file mode 100644 index 0000000000..7c89c9a5a4 --- /dev/null +++ b/elf/libtracemod5-1.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..f5a4028003 --- /dev/null +++ b/scripts/tst-ld-trace.py @@ -0,0 +1,108 @@ +#!/usr/bin/python3 +# Dump the output of LD_TRACE_LOADED_OBJECTS in architecture neutral format. +# 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 subprocess +import sys + +try: + subprocess.run +except: + class _CompletedProcess: + def __init__(self, args, returncode, stdout=None, stderr=None): + self.args = args + self.returncode = returncode + self.stdout = stdout + self.stderr = stderr + + def _run(*popenargs, input=None, timeout=None, check=False, **kwargs): + assert(timeout is None) + with subprocess.Popen(*popenargs, **kwargs) as process: + try: + stdout, stderr = process.communicate(input) + except: + process.kill() + process.wait() + raise + returncode = process.poll() + if check and returncode: + raise subprocess.CalledProcessError(returncode, popenargs) + return _CompletedProcess(popenargs, returncode, stdout, stderr) + + subprocess.run = _run + +def is_vdso(lib): + return lib.startswith('linux-gate') or lib.startswith('linux-vdso') + + +def parse_trace(cmd, fref): + new_env = os.environ.copy() + new_env['LD_TRACE_LOADED_OBJECTS'] = '1' + trace_out = subprocess.run(cmd, stdout=subprocess.PIPE, check=True, + universal_newlines=True, env=new_env).stdout + trace = [] + for line in trace_out.splitlines(): + 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)] + trace = sorted(trace) + + reference = sorted(line.replace('\n','') for line in fref.readlines()) + + ret = 0 if 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 trace: {}".format(i)) + + sys.exit(ret) + + +def get_parser(): + parser = argparse.ArgumentParser(description=__doc__) + parser.add_argument('command', + help='comand to run') + 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.reference, 'r') as fref: + # Remove the initial 'env' command. + parse_trace(opts.command.split()[1:], fref) + + +if __name__ == '__main__': + main(sys.argv[1:])