From fdeeb62e28f7b79fd2222d14da454aab72af2f00 Mon Sep 17 00:00:00 2001
From: Michael Matz <matz@suse.de>
Date: Mon, 20 Jan 2020 05:31:09 +0100
Subject: [PATCH] Fix symbol versions with shared libs
ELF files that refer to shared libs containing sym-versions, but
don't refer to any dynamic symbols with symbol versions (should happen
only with very simple shared libs) would generate an empty .gnu.version_r
section. Some dynamic linker contain bugs in that they don't check
the section size or DT_VERNEEDNUM (which are both zero for such files
we generate) before accessing the first entry, and then bail out with
a message like
./a.exe: error while loading shared libraries: ./a1.so: unsupported
version 25960 of Verneed record
(where the "version number" actually comes from neighboring bytes
from different sections).
So, there's not much choice, we simply must not generate such section.
---
tccelf.c | 86 ++++++++++++++++++++++++++++++--------------------------
1 file changed, 46 insertions(+), 40 deletions(-)
diff --git a/tccelf.c b/tccelf.c
index fe00a30f..de81e33c 100644
--- a/tccelf.c
+++ b/tccelf.c
@@ -558,9 +558,7 @@ version_add (TCCState *s1)
return;
versym_section = new_section(s1, ".gnu.version", SHT_GNU_versym, SHF_ALLOC);
versym_section->sh_entsize = sizeof(ElfW(Half));
- verneed_section = new_section(s1, ".gnu.version_r", SHT_GNU_verneed, SHF_ALLOC);
versym_section->link = s1->dynsym;
- verneed_section->link = s1->dynsym->link;
/* add needed symbols */
symtab = s1->dynsym;
@@ -580,43 +578,50 @@ version_add (TCCState *s1)
} else
versym[sym_index] = 0;
}
- /* generate verneed section */
- for (i = nb_sym_versions; i-- > 0;) {
- struct sym_version *sv = &sym_versions[i];
- int n_same_libs = 0, prev;
- size_t vnofs;
- ElfW(Vernaux) *vna = 0;
- if (sv->out_index < 1)
- continue;
- vnofs = section_add(verneed_section, sizeof(*vn), 1);
- vn = (ElfW(Verneed)*)(verneed_section->data + vnofs);
- vn->vn_version = 1;
- vn->vn_file = put_elf_str(verneed_section->link, sv->lib);
- vn->vn_aux = sizeof (*vn);
- do {
- prev = sv->prev_same_lib;
- if (sv->out_index > 0) {
- vna = section_ptr_add(verneed_section, sizeof(*vna));
- vna->vna_hash = elf_hash ((const unsigned char *)sv->version);
- vna->vna_flags = 0;
- vna->vna_other = sv->out_index;
- sv->out_index = -2;
- vna->vna_name = put_elf_str(verneed_section->link, sv->version);
- vna->vna_next = sizeof (*vna);
- n_same_libs++;
- }
- if (prev >= 0)
- sv = &sym_versions[prev];
- } while(prev >= 0);
- vna->vna_next = 0;
- vn = (ElfW(Verneed)*)(verneed_section->data + vnofs);
- vn->vn_cnt = n_same_libs;
- vn->vn_next = sizeof(*vn) + n_same_libs * sizeof(*vna);
- nb_entries++;
+ /* generate verneed section, but not when it will be empty. Some
+ dynamic linkers look at their contents even when DTVERNEEDNUM and
+ section size is zero. */
+ if (nb_versions > 2) {
+ verneed_section = new_section(s1, ".gnu.version_r",
+ SHT_GNU_verneed, SHF_ALLOC);
+ verneed_section->link = s1->dynsym->link;
+ for (i = nb_sym_versions; i-- > 0;) {
+ struct sym_version *sv = &sym_versions[i];
+ int n_same_libs = 0, prev;
+ size_t vnofs;
+ ElfW(Vernaux) *vna = 0;
+ if (sv->out_index < 1)
+ continue;
+ vnofs = section_add(verneed_section, sizeof(*vn), 1);
+ vn = (ElfW(Verneed)*)(verneed_section->data + vnofs);
+ vn->vn_version = 1;
+ vn->vn_file = put_elf_str(verneed_section->link, sv->lib);
+ vn->vn_aux = sizeof (*vn);
+ do {
+ prev = sv->prev_same_lib;
+ if (sv->out_index > 0) {
+ vna = section_ptr_add(verneed_section, sizeof(*vna));
+ vna->vna_hash = elf_hash ((const unsigned char *)sv->version);
+ vna->vna_flags = 0;
+ vna->vna_other = sv->out_index;
+ sv->out_index = -2;
+ vna->vna_name = put_elf_str(verneed_section->link, sv->version);
+ vna->vna_next = sizeof (*vna);
+ n_same_libs++;
+ }
+ if (prev >= 0)
+ sv = &sym_versions[prev];
+ } while(prev >= 0);
+ vna->vna_next = 0;
+ vn = (ElfW(Verneed)*)(verneed_section->data + vnofs);
+ vn->vn_cnt = n_same_libs;
+ vn->vn_next = sizeof(*vn) + n_same_libs * sizeof(*vna);
+ nb_entries++;
+ }
+ if (vn)
+ vn->vn_next = 0;
+ verneed_section->sh_info = nb_entries;
}
- if (vn)
- vn->vn_next = 0;
- verneed_section->sh_info = nb_entries;
dt_verneednum = nb_entries;
}
#endif
@@ -2045,10 +2050,11 @@ static void fill_dynamic(TCCState *s1, struct dyn_inf *dyninf)
put_dt(dynamic, DT_RELENT, sizeof(ElfW_Rel));
#endif
#endif
- if (versym_section) {
+ if (versym_section)
+ put_dt(dynamic, DT_VERSYM, versym_section->sh_addr);
+ if (verneed_section) {
put_dt(dynamic, DT_VERNEED, verneed_section->sh_addr);
put_dt(dynamic, DT_VERNEEDNUM, dt_verneednum);
- put_dt(dynamic, DT_VERSYM, versym_section->sh_addr);
}
s = find_section_create (s1, ".preinit_array", 0);
if (s && s->data_offset) {