backends: Always use elf_getshdrstrndx in check_special_symbol.

The check_special_symbol backend functions used the Ehdr e_shstrndx
field to get at the name of sections. This is not correct if there
are more than SHN_LORESERVE sections. Always use elf_getshdrstrndx
to get the shstrtab section. And drop the Ehdr argument that isn't
necessary anymore.

Signed-off-by: Mark Wielaard <mark@klomp.org>

6 files changed, 31 insertions, 10 deletions

diff --git a/backends/ChangeLog b/backends/ChangeLog
index 52149482..ada349fe 100644
--- a/backends/ChangeLog
+++ b/backends/ChangeLog
@@ -1,3 +1,13 @@
+2018-09-12  Mark Wielaard  <mark@klomp.org>
+
+	* aarch64_symbol.c (aarch64_check_special_symbol): Drop ehdr argument,
+	use elf_getshdrstrndx.
+	* alpha_symbol.c (alpha_check_special_symbol): Drop ehdr argument.
+	* ppc64_symbol.c (ppc64_check_special_symbol): Likewise and use
+	elf_getshdrstrndx.
+	* ppc_symbol.c (ppc_check_special_symbol): Likewise.
+	* riscv_symbol.c (riscv_check_special_symbol): Likewise.
+
 2018-07-21  Andreas Schwab  <schwab@linux-m68k.org>
 
 	* Makefile.am (m68k_SRCS): Add m68k_cfi.c and m68k_initreg.c.
diff --git a/backends/aarch64_symbol.c b/backends/aarch64_symbol.c
index da3382e9..dfd755a5 100644
--- a/backends/aarch64_symbol.c
+++ b/backends/aarch64_symbol.c
@@ -62,13 +62,16 @@ aarch64_reloc_simple_type (Ebl *ebl __attribute__ ((unused)), int type)
    https://bugzilla.redhat.com/show_bug.cgi?id=1201778
  */
 bool
-aarch64_check_special_symbol (Elf *elf, GElf_Ehdr *ehdr, const GElf_Sym *sym,
+aarch64_check_special_symbol (Elf *elf, const GElf_Sym *sym,
                               const char *name, const GElf_Shdr *destshdr)
 {
   if (name != NULL
       && strcmp (name, "_GLOBAL_OFFSET_TABLE_") == 0)
     {
-      const char *sname = elf_strptr (elf, ehdr->e_shstrndx, destshdr->sh_name);
+      size_t shstrndx;
+      if (elf_getshdrstrndx (elf, &shstrndx) != 0)
+	return false;
+      const char *sname = elf_strptr (elf, shstrndx, destshdr->sh_name);
       if (sname != NULL
 	  && (strcmp (sname, ".got") == 0 || strcmp (sname, ".got.plt") == 0))
 	{
@@ -79,7 +82,7 @@ aarch64_check_special_symbol (Elf *elf, GElf_Ehdr *ehdr, const GElf_Sym *sym,
 	      GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
 	      if (shdr != NULL)
 		{
-		  sname = elf_strptr (elf, ehdr->e_shstrndx, shdr->sh_name);
+		  sname = elf_strptr (elf, shstrndx, shdr->sh_name);
 		  if (sname != NULL && strcmp (sname, ".got") == 0)
 		    return (sym->st_value >= shdr->sh_addr
 			    && sym->st_value < shdr->sh_addr + shdr->sh_size);
diff --git a/backends/alpha_symbol.c b/backends/alpha_symbol.c
index 657d9eec..b7f7c17a 100644
--- a/backends/alpha_symbol.c
+++ b/backends/alpha_symbol.c
@@ -130,7 +130,6 @@ alpha_check_special_section (Ebl *ebl,
    normal checks.  */
 bool
 alpha_check_special_symbol (Elf *elf __attribute__ ((unused)),
-			    GElf_Ehdr *ehdr __attribute__ ((unused)),
 			    const GElf_Sym *sym __attribute__ ((unused)),
 			    const char *name,
 			    const GElf_Shdr *destshdr __attribute__ ((unused)))
diff --git a/backends/ppc64_symbol.c b/backends/ppc64_symbol.c
index 0feddcee..40ba4f74 100644
--- a/backends/ppc64_symbol.c
+++ b/backends/ppc64_symbol.c
@@ -94,12 +94,15 @@ ppc64_dynamic_tag_check (int64_t tag)
 /* Check whether given symbol's st_value and st_size are OK despite failing
    normal checks.  */
 bool
-ppc64_check_special_symbol (Elf *elf, GElf_Ehdr *ehdr,
+ppc64_check_special_symbol (Elf *elf,
 			    const GElf_Sym *sym __attribute__ ((unused)),
 			    const char *name __attribute__ ((unused)),
 			    const GElf_Shdr *destshdr)
 {
-  const char *sname = elf_strptr (elf, ehdr->e_shstrndx, destshdr->sh_name);
+  size_t shstrndx;
+  if (elf_getshdrstrndx (elf, &shstrndx) != 0)
+    return false;
+  const char *sname = elf_strptr (elf, shstrndx, destshdr->sh_name);
   if (sname == NULL)
     return false;
   return strcmp (sname, ".opd") == 0;
diff --git a/backends/ppc_symbol.c b/backends/ppc_symbol.c
index 4b32003a..35b14319 100644
--- a/backends/ppc_symbol.c
+++ b/backends/ppc_symbol.c
@@ -135,7 +135,7 @@ find_dyn_got (Elf *elf, GElf_Addr *addr)
 /* Check whether given symbol's st_value and st_size are OK despite failing
    normal checks.  */
 bool
-ppc_check_special_symbol (Elf *elf, GElf_Ehdr *ehdr, const GElf_Sym *sym,
+ppc_check_special_symbol (Elf *elf, const GElf_Sym *sym,
 			  const char *name, const GElf_Shdr *destshdr)
 {
   if (name == NULL)
@@ -152,7 +152,10 @@ ppc_check_special_symbol (Elf *elf, GElf_Ehdr *ehdr, const GElf_Sym *sym,
       return true;
     }
 
-  const char *sname = elf_strptr (elf, ehdr->e_shstrndx, destshdr->sh_name);
+  size_t shstrndx;
+  if (elf_getshdrstrndx (elf, &shstrndx) != 0)
+    return false;
+  const char *sname = elf_strptr (elf, shstrndx, destshdr->sh_name);
   if (sname == NULL)
     return false;
 
diff --git a/backends/riscv_symbol.c b/backends/riscv_symbol.c
index dce8e358..866a2d7a 100644
--- a/backends/riscv_symbol.c
+++ b/backends/riscv_symbol.c
@@ -64,13 +64,16 @@ riscv_machine_flag_check (GElf_Word flags)
 /* Check whether given symbol's st_value and st_size are OK despite failing
    normal checks.  */
 bool
-riscv_check_special_symbol (Elf *elf, GElf_Ehdr *ehdr, const GElf_Sym *sym,
+riscv_check_special_symbol (Elf *elf, const GElf_Sym *sym,
 			    const char *name, const GElf_Shdr *destshdr)
 {
   if (name == NULL)
     return false;
 
-  const char *sname = elf_strptr (elf, ehdr->e_shstrndx, destshdr->sh_name);
+  size_t shstrndx;
+  if (elf_getshdrstrndx (elf, &shstrndx) != 0)
+    return false;
+  const char *sname = elf_strptr (elf, shstrndx, destshdr->sh_name);
   if (sname == NULL)
     return false;