[Bug tools/32864] "eu-readelf: bad dynamic symbol" error on ELF without DT_VERSYM
https://sourceware.org/bugzilla/show_bug.cgi?id=32864 Aaron Merey changed: What|Removed |Added CC||amerey at redhat dot com --- Comment #2 from Aaron Merey --- Thanks for the detailed bug report. I've posted a patch to elfutils-devel based on your sample patch. https://sourceware.org/pipermail/elfutils-devel/2025q2/008084.html -- You are receiving this mail because: You are on the CC list for the bug.
[PATCH] src/readelf.c: Access symbol and version data only if available
handle_dynamic_symtab can attempt to read symbol and version data from file offset 0 if the associated DT_ tags aren't found. Fix this by only reading symbol and version data when non-zero file offsets have been found. https://sourceware.org/bugzilla/show_bug.cgi?id=32864 Suggested-by: Constantine Bytensky Signed-off-by: Aaron Merey --- src/readelf.c | 50 +++--- 1 file changed, 31 insertions(+), 19 deletions(-) diff --git a/src/readelf.c b/src/readelf.c index 5b0e7b47..0452977f 100644 --- a/src/readelf.c +++ b/src/readelf.c @@ -3047,18 +3047,25 @@ handle_dynamic_symtab (Ebl *ebl) Elf_Data *verdef_data = NULL; Elf_Data *verneed_data = NULL; - symdata = elf_getdata_rawchunk ( - ebl->elf, offs[i_symtab], - gelf_fsize (ebl->elf, ELF_T_SYM, syments, EV_CURRENT), ELF_T_SYM); - symstrdata = elf_getdata_rawchunk (ebl->elf, offs[i_strtab], addrs[i_strsz], - ELF_T_BYTE); - versym_data = elf_getdata_rawchunk ( - ebl->elf, offs[i_versym], syments * sizeof (Elf64_Half), ELF_T_HALF); + if (offs[i_symtab] != 0) +symdata = elf_getdata_rawchunk ( + ebl->elf, offs[i_symtab], + gelf_fsize (ebl->elf, ELF_T_SYM, syments, EV_CURRENT), ELF_T_SYM); + + if (offs[i_strtab] != 0) +symstrdata = elf_getdata_rawchunk (ebl->elf, offs[i_strtab], addrs[i_strsz], + ELF_T_BYTE); + + if (offs[i_versym] != 0) +versym_data = elf_getdata_rawchunk ( + ebl->elf, offs[i_versym], syments * sizeof (Elf64_Half), ELF_T_HALF); /* Get the verneed_data without vernaux. */ - verneed_data = elf_getdata_rawchunk ( - ebl->elf, offs[i_verneed], addrs[i_verneednum] * sizeof (Elf64_Verneed), - ELF_T_VNEED); + if (offs[i_verneed] != 0) +verneed_data = elf_getdata_rawchunk ( + ebl->elf, offs[i_verneed], addrs[i_verneednum] * sizeof (Elf64_Verneed), + ELF_T_VNEED); + size_t vernauxnum = 0; size_t vn_next_offset = 0; @@ -3071,14 +3078,18 @@ handle_dynamic_symtab (Ebl *ebl) } /* Update the verneed_data to include the vernaux. */ - verneed_data = elf_getdata_rawchunk ( - ebl->elf, offs[i_verneed], - (addrs[i_verneednum] + vernauxnum) * sizeof (GElf_Verneed), ELF_T_VNEED); + if (offs[i_verneed] != 0) +verneed_data = elf_getdata_rawchunk ( + ebl->elf, offs[i_verneed], + (addrs[i_verneednum] + vernauxnum) * sizeof (GElf_Verneed), + ELF_T_VNEED); /* Get the verdef_data without verdaux. */ - verdef_data = elf_getdata_rawchunk ( - ebl->elf, offs[i_verdef], addrs[i_verdefnum] * sizeof (Elf64_Verdef), - ELF_T_VDEF); + if (offs[i_verdef] != 0) +verdef_data = elf_getdata_rawchunk ( + ebl->elf, offs[i_verdef], addrs[i_verdefnum] * sizeof (Elf64_Verdef), + ELF_T_VDEF); + size_t verdauxnum = 0; size_t vd_next_offset = 0; @@ -3091,9 +3102,10 @@ handle_dynamic_symtab (Ebl *ebl) } /* Update the verdef_data to include the verdaux. */ - verdef_data = elf_getdata_rawchunk ( - ebl->elf, offs[i_verdef], - (addrs[i_verdefnum] + verdauxnum) * sizeof (GElf_Verdef), ELF_T_VDEF); + if (offs[i_verdef] != 0) +verdef_data = elf_getdata_rawchunk ( + ebl->elf, offs[i_verdef], + (addrs[i_verdefnum] + verdauxnum) * sizeof (GElf_Verdef), ELF_T_VDEF); unsigned int nsyms = (unsigned int)syments; process_symtab (ebl, nsyms, 0, 0, 0, symdata, versym_data, symstrdata, -- 2.49.0
Re: [PATCH v2] libdwfl: resolve all paths relative to sysroot
Hi Michal,
On Tue, Apr 1, 2025 at 2:56 PM Michal Sekletar wrote:
>
> Whenever possible, resolve all symlinks as if the sysroot path were a
> chroot environment. This prevents potential interactions with files from
> the host filesystem.
>
> Signed-off-by: Michal Sekletar
> ---
> configure.ac | 26 ++
> libdwfl/dwfl_segment_report_module.c | 39 +--
> libdwfl/link_map.c | 32 +-
> tests/run-sysroot.sh | 32 ++
> tests/testfile-sysroot-link.tar.bz2 | Bin 0 -> 2334030 bytes
> 5 files changed, 120 insertions(+), 9 deletions(-)
> create mode 100644 tests/testfile-sysroot-link.tar.bz2
>
> diff --git a/configure.ac b/configure.ac
> index 1679a17d..27ea7153 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -283,6 +283,32 @@ case "$CFLAGS" in
> ;;
> esac
>
> +AC_CACHE_CHECK(
> + [for openat2 with RESOLVE_IN_ROOT support],
> + [eu_cv_openat2_RESOLVE_IN_ROOT],
> + [AC_LINK_IFELSE(
> +[AC_LANG_PROGRAM(
> + [[#define _GNU_SOURCE
> +#include
> +#include
> +#include
> +#include
> +#include
> +#include
> + ]], [[
> +struct open_how how = { .flags = O_RDONLY|O_DIRECTORY, .resolve =
> RESOLVE_IN_ROOT };
> +int dfd = open (".", O_PATH);
> +return syscall (SYS_openat2, dfd, ".", &how, sizeof(how)) < 0;
> + ]]
> +)],
> +[eu_cv_openat2_RESOLVE_IN_ROOT=yes],
> +[eu_cv_openat2_RESOLVE_IN_ROOT=no]
> + )]
> +)
> +AS_IF([test "x$eu_cv_openat2_RESOLVE_IN_ROOT" = xyes],
> + [AC_DEFINE([HAVE_OPENAT2_RESOLVE_IN_ROOT], [1], [Define if openat2 is
> available])]
> +)
> +
> dnl enable debugging of branch prediction.
> AC_ARG_ENABLE([debugpred],
> AS_HELP_STRING([--enable-debugpred],[build binaries with support to debug
> branch prediction]),
> diff --git a/libdwfl/dwfl_segment_report_module.c
> b/libdwfl/dwfl_segment_report_module.c
> index 32f44af8..ee723114 100644
> --- a/libdwfl/dwfl_segment_report_module.c
> +++ b/libdwfl/dwfl_segment_report_module.c
> @@ -37,6 +37,12 @@
> #include
> #include
>
> +#if HAVE_OPENAT2_RESOLVE_IN_ROOT
> +#include
> +#include
> +#include
> +#endif
> +
> #include
>
>
> @@ -784,18 +790,35 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const
> char *name,
> sysroot if it is set. */
>if (dwfl->sysroot && !executable)
> {
> - int r;
> - char *n;
> +#ifdef HAVE_OPENAT2_RESOLVE_IN_ROOT
> + int sysrootfd;
> + struct open_how how = {
> + .flags = O_RDONLY,
> + .resolve = RESOLVE_IN_ROOT,
> + };
> +
> + sysrootfd = open (dwfl->sysroot, O_DIRECTORY|O_PATH);
> + if (sysrootfd < 0)
> + return -1;
>
> - r = asprintf (&n, "%s%s", dwfl->sysroot, name);
> - if (r > 0)
> + fd = syscall (SYS_openat2, sysrootfd, name, &how, sizeof(how));
> + close (sysrootfd);
> +
> + if (fd < 0 && errno == ENOSYS)
> +#endif
> {
> - fd = open (n, O_RDONLY);
> - free (n);
> + int r;
> + char *n;
> + r = asprintf (&n, "%s%s", dwfl->sysroot, name);
> + if (r > 0)
> + {
> + fd = open (n, O_RDONLY);
> + free (n);
> + }
> }
> -}
> + }
>else
> - fd = open (name, O_RDONLY);
> + fd = open (name, O_RDONLY);
>
>if (fd >= 0)
> {
> diff --git a/libdwfl/link_map.c b/libdwfl/link_map.c
> index 8ab14862..c52ed041 100644
> --- a/libdwfl/link_map.c
> +++ b/libdwfl/link_map.c
> @@ -34,6 +34,12 @@
>
> #include
>
> +#if HAVE_OPENAT2_RESOLVE_IN_ROOT
> +#include
> +#include
> +#include
> +#endif
> +
> /* This element is always provided and always has a constant value.
> This makes it an easy thing to scan for to discern the format. */
> #define PROBE_TYPE AT_PHENT
> @@ -418,7 +424,30 @@ report_r_debug (uint_fast8_t elfclass, uint_fast8_t
> elfdata,
> /* This code is mostly inlined dwfl_report_elf. */
> char *sysroot_name = NULL;
> const char *sysroot = dwfl->sysroot;
> + int fd;
> +
> +#ifdef HAVE_OPENAT2_RESOLVE_IN_ROOT
> + if (sysroot)
> + {
> + int sysrootfd;
> +
> + struct open_how how = {
> + .flags = O_RDONLY,
> + .resolve = RESOLVE_IN_ROOT,
> + };
>
> + sysrootfd = open (sysroot, O_DIRECTORY|O_PATH);
> + if (sysrootfd < 0)
> + return -1;
> +
> + fd = syscall (SYS_openat2, sysrootfd, name, &how, sizeof(how));
> + close (sysrootfd);
> +
> + /* Fallback to regular open() is openat2 is not available. */
> + if (fd < 0 && errno == ENOSYS)
> + fd = open (name, O_RDONLY);
> + }
Re: [PATCH] libdw: Add Nim language and dwarf_srclang tests
Hi Mark, On Wed, Apr 2, 2025 at 8:50 AM Mark Wielaard wrote: > > DW_LANG_Nim and DW_LNAME_Nim were added to the DWARF languages. > > While adding them, and the default lower bounds, I noticed DW_LANG_V > and DW_LANG_Algol68 where missing in srclang_to_language an internal > helper function. > > Testing through the public api is not that easy since you need a > Dwarf_Die with the right attributes. So this patch adds a way to > compile an individual source file with an optional main function that > can directly access the internal/static functions. > > Note that it is almost generic. But even though using .SECONDEXPANSION > I couldn't figure out how to create the equivalent of a rule starting > with %_check$(EXEEXT) target. So for now the rule has to repeated for > every new _check TEST. And there needs to be a line to tell make dist > to not expect the fake source: nodist_src_check_SOURCES = src_check.c > > The new test pointed out that there were a few more bugs with > DW_LANG_Dylan and DW_LNAME_Mojo. Also fix those. > > * libdw/dwarf.h: Add DW_LANG_Nim and DW_LNAME_Nim. > * libdw/Makefile.am: Add check_PROGRAMS and TESTS for > dwarf_srclang_check. > * libdw/dwarf_default_lower_bound.c > (dwarf_default_lower_bound): Add DW_LANG_Nim. > (dwarf_language_lower_bound): Add DW_LNAME_Nim. > * libdw/dwarf_srclang.c (srclang_to_language): Handle > DW_LANG_Dylan, DW_LANG_V, DW_LANG_Algol68 and DW_LANG_Nim. > (language_to_srclang): Fix DW_LNAME_Mojo. Add DW_LNAME_Nim. > (test_lang): New function guarded by MAIN_CHECK. > (main): Likewise. > > Signed-off-by: Mark Wielaard LGTM. The optional main function approach opens up a lot of possibilities for testing static functions throughout all elfutils libraries. Aaron
