On Tue, Jul 17, 2012 at 05:50:28PM +0200, Mark Wielaard wrote: > The asserts seem too aggressive/wrong in this case. The following > comment in elf32_getshdr.c (load_shdr_wrlock) explains them: > > /* All the data is already mapped. If we could use it > directly this would already have happened. */ > > But in the case of elf_cntl (ELF_CREAD) this has not yet happened, > unless you already accessed the shdrs before that call.
I think the best solution is to just adjust the asserts to take this into account. Which is what the attached patch does. It also includes a testcase. Comments? Thanks, Mark
>From c82168e41ec929e42653b7d1b465b79ae6451174 Mon Sep 17 00:00:00 2001 From: Mark Wielaard <[email protected]> Date: Wed, 18 Jul 2012 13:14:30 +0200 Subject: [PATCH] elf_getshdr should work for elf->flags & ELF_F_MALLOCED. Reported-by: Nick Alcock <[email protected]> Signed-off-by: Mark Wielaard <[email protected]> --- libelf/ChangeLog | 5 ++ libelf/elf32_getshdr.c | 9 ++- tests/ChangeLog | 8 +++ tests/Makefile.am | 6 ++- tests/run-elf_cntl_gelf_getshdr.sh | 30 +++++++++++ tests/test-elf_cntl_gelf_getshdr.c | 102 ++++++++++++++++++++++++++++++++++++ 6 files changed, 155 insertions(+), 5 deletions(-) create mode 100755 tests/run-elf_cntl_gelf_getshdr.sh create mode 100644 tests/test-elf_cntl_gelf_getshdr.c diff --git a/libelf/ChangeLog b/libelf/ChangeLog index 89dd35f..1c1f7c8 100644 --- a/libelf/ChangeLog +++ b/libelf/ChangeLog @@ -1,3 +1,8 @@ +2012-07-19 Mark Wielaard <[email protected]> + + * elf32_getshdr.c (load_shdr_wrlock): Add elf->flags & ELF_F_MALLOCED + to asserts. + 2012-04-02 Mark Wielaard <[email protected]> * elf32_offscn.c: Do not match SHT_NOBITS sections at OFFSET unless diff --git a/libelf/elf32_getshdr.c b/libelf/elf32_getshdr.c index f0319cb..6bd065b 100644 --- a/libelf/elf32_getshdr.c +++ b/libelf/elf32_getshdr.c @@ -80,11 +80,14 @@ load_shdr_wrlock (Elf_Scn *scn) ElfW2(LIBELFBITS,Shdr) *notcvt; /* All the data is already mapped. If we could use it - directly this would already have happened. */ + directly this would already have happened. Unless + we allocated the memory ourselves and the ELF_F_MALLOCED + flag is set. */ void *file_shdr = ((char *) elf->map_address + elf->start_offset + ehdr->e_shoff); - assert (ehdr->e_ident[EI_DATA] != MY_ELFDATA + assert (elf->flags & ELF_F_MALLOCED + || ehdr->e_ident[EI_DATA] != MY_ELFDATA || (! ALLOW_UNALIGNED && ((uintptr_t) file_shdr & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1)) != 0)); @@ -92,7 +95,7 @@ load_shdr_wrlock (Elf_Scn *scn) /* Now copy the data and at the same time convert the byte order. */ if (ehdr->e_ident[EI_DATA] == MY_ELFDATA) { - assert (! ALLOW_UNALIGNED); + assert (elf->flags & ELF_F_MALLOCED || ! ALLOW_UNALIGNED); memcpy (shdr, file_shdr, size); } else diff --git a/tests/ChangeLog b/tests/ChangeLog index 9d17c7e..2b0e806 100644 --- a/tests/ChangeLog +++ b/tests/ChangeLog @@ -1,3 +1,11 @@ +2012-07-19 Mark Wielaard <[email protected]> + + * Makefile.am (check_PROGRAMS): Add test-elf_cntl_gelf_getshdr. + (TESTS): Add run-elf_cntl_gelf_getshdr.sh. + (test_elf_cntl_gelf_getshdr_LDADD): New. + test-elf_cntl_gelf_getshdr.c: New test program. + run-elf_cntl_gelf_getshdr.sh: New test script. + 2012-06-26 Mike Frysinger <[email protected]> * Makefile.am (check_PROGRAMS): Rename from noinst_PROGRAMS. diff --git a/tests/Makefile.am b/tests/Makefile.am index ae9839f..cb3df9f 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -50,7 +50,8 @@ check_PROGRAMS = arextract arsymtest newfile saridx scnnames sectiondump \ dwfl-addr-sect dwfl-bug-report early-offscn \ dwfl-bug-getmodules dwarf-getmacros addrcfi \ test-flag-nobits dwarf-getstring rerequest_tag \ - alldts md5-sha1-test typeiter low_high_pc + alldts md5-sha1-test typeiter low_high_pc \ + test-elf_cntl_gelf_getshdr asm_TESTS = asm-tst1 asm-tst2 asm-tst3 asm-tst4 asm-tst5 \ asm-tst6 asm-tst7 asm-tst8 asm-tst9 @@ -80,7 +81,7 @@ TESTS = run-arextract.sh run-arsymtest.sh newfile test-nlist \ run-test-flag-nobits.sh run-prelink-addr-test.sh \ run-dwarf-getstring.sh run-rerequest_tag.sh run-typeiter.sh \ run-readelf-d.sh run-unstrip-n.sh run-low_high_pc.sh \ - run-macro-test.sh + run-macro-test.sh run-elf_cntl_gelf_getshdr.sh if !STANDALONE check_PROGRAMS += msg_tst md5-sha1-test @@ -259,6 +260,7 @@ alldts_LDADD = $(libebl) $(libelf) $(libmudflap) md5_sha1_test_LDADD = $(libeu) typeiter_LDADD = $(libdw) $(libelf) $(libmudflap) low_high_pc_LDADD = $(libdw) $(libelf) $(libmudflap) +test_elf_cntl_gelf_getshdr_LDADD = $(libelf) $(libmudflap) if GCOV check: check-am coverage diff --git a/tests/run-elf_cntl_gelf_getshdr.sh b/tests/run-elf_cntl_gelf_getshdr.sh new file mode 100755 index 0000000..41a7d15 --- /dev/null +++ b/tests/run-elf_cntl_gelf_getshdr.sh @@ -0,0 +1,30 @@ +#! /bin/sh +# Copyright (C) 2012 Red Hat, Inc. +# This file is part of elfutils. +# +# This file is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# elfutils 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 General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. + +. $srcdir/test-subr.sh + +# However we open the elf file, the shdrs should be the same. +testrun ./test-elf_cntl_gelf_getshdr READ test-elf_cntl_gelf_getshdr \ + > test_shdr.out + +testrun_compare ./test-elf_cntl_gelf_getshdr MMAP test-elf_cntl_gelf_getshdr \ + < test_shdr.out + +testrun_compare ./test-elf_cntl_gelf_getshdr FDREAD test-elf_cntl_gelf_getshdr \ + < test_shdr.out + +rm -f test_shdr.out diff --git a/tests/test-elf_cntl_gelf_getshdr.c b/tests/test-elf_cntl_gelf_getshdr.c new file mode 100644 index 0000000..9e4b417 --- /dev/null +++ b/tests/test-elf_cntl_gelf_getshdr.c @@ -0,0 +1,102 @@ +/* Copyright (C) 2012 Red Hat, Inc. + This file is part of elfutils. + + This file is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + elfutils 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ + +#include <sys/types.h> +#include <sys/stat.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <errno.h> +#include <string.h> +#include <fcntl.h> +#include <gelf.h> +#include <libelf.h> +#include <stdbool.h> +#include <inttypes.h> + +int +main (int argc, char *argv[]) +{ + if (argc != 3) + { + fprintf (stderr, "Needs two arguments.\n"); + fprintf (stderr, "First needs to be 'READ', 'MMAP' or 'FDREAD'\n"); + fprintf (stderr, "Second is the ELF file to read.\n"); + exit (-1); + } + + bool do_mmap = false; + bool close_fd = false; + if (strcmp (argv[1], "READ") == 0) + { + do_mmap = false; + close_fd = false; + } + else if (strcmp (argv[1], "MMAP") == 0) + { + do_mmap = true; + close_fd = false; + } + else if (strcmp (argv[1], "FDREAD") == 0) + { + do_mmap = false; + close_fd = true; + } + else + { + fprintf (stderr, "First arg needs to be 'READ', 'MMAP' or 'FDREAD'\n"); + exit (-1); + } + + elf_version (EV_CURRENT); + + int fd; + if ((fd = open (argv[2], O_RDONLY)) < 0) + { + fprintf (stderr, "Cannot open input file %s: %s\n", argv[2], + strerror (errno)); + exit (-1); + } + + Elf *elf = elf_begin (fd, do_mmap ? ELF_C_READ_MMAP : ELF_C_READ, NULL); + if (elf == NULL) + { + fprintf (stderr, "elf_begin failed for %s: %s\n", argv[2], + elf_errmsg (-1)); + exit (-1); + } + + if (! do_mmap && close_fd) + { + if (elf_cntl (elf, ELF_C_FDREAD) < 0) + { + fprintf (stderr, "elf_cntl failed for %s: %s\n", argv[2], + elf_errmsg (-1)); + exit (-1); + } + close (fd); + } + + Elf_Scn *scn = NULL; + while ((scn = elf_nextscn (elf, scn)) != NULL) + { + GElf_Shdr shdr_mem; + GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); + printf ("Section at offset %#0" PRIx64 "\n", shdr->sh_offset); + } + + elf_end (elf); +} -- 1.7.7.6
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