strip: Add more NULL check

When gelf_getshdr, gelf_getrela, gelf_getrel or gelf_getsymshndx
return NULL it is an internal error which we want to report instead of
crashing.

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

diff --git a/src/ChangeLog b/src/ChangeLog
index ae09eb1..8c9f5dd 100644 (file)
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2022-05-09  Mark Wielaard  <mark@klomp.org>
+
+       * strip.c (remove_debug_relocations): Check gelf_getshdr, gelf_getrela,
+       gelf_getrel and gelf_getsymshndx don't return NULL.
+
 2022-05-10  Mark Wielaard  <mark@klomp.org>
 
        * elfcompress.c (process_file): Sanity check shstrtab_name,

diff --git a/src/strip.c b/src/strip.c
index 30a1f9d..452b127 100644 (file)
--- a/src/strip.c
+++ b/src/strip.c
@@ -576,7 +576,8 @@ remove_debug_relocations (Ebl *ebl, Elf *elf, GElf_Ehdr *ehdr,
         might want to change the size.  */
       GElf_Shdr shdr_mem;
       GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
-      if (shdr->sh_type == SHT_REL || shdr->sh_type == SHT_RELA)
+      if (shdr != NULL
+         && (shdr->sh_type == SHT_REL || shdr->sh_type == SHT_RELA))
        {
          /* Make sure that this relocation section points to a
             section to relocate with contents, that isn't
@@ -584,7 +585,8 @@ remove_debug_relocations (Ebl *ebl, Elf *elf, GElf_Ehdr *ehdr,
          Elf_Scn *tscn = elf_getscn (elf, shdr->sh_info);
          GElf_Shdr tshdr_mem;
          GElf_Shdr *tshdr = gelf_getshdr (tscn, &tshdr_mem);
-         if (tshdr->sh_type == SHT_NOBITS
+         if (tshdr == NULL
+             || tshdr->sh_type == SHT_NOBITS
              || tshdr->sh_size == 0
              || (tshdr->sh_flags & SHF_ALLOC) != 0)
            continue;
@@ -653,6 +655,8 @@ remove_debug_relocations (Ebl *ebl, Elf *elf, GElf_Ehdr *ehdr,
              if (is_rela)
                {
                  GElf_Rela *r = gelf_getrela (reldata, relidx, &mem.rela);
+                 if (r == NULL)
+                   INTERNAL_ERROR (fname);
                  offset = r->r_offset;
                  addend = r->r_addend;
                  rtype = GELF_R_TYPE (r->r_info);
@@ -662,6 +666,8 @@ remove_debug_relocations (Ebl *ebl, Elf *elf, GElf_Ehdr *ehdr,
              else
                {
                  GElf_Rel *r = gelf_getrel (reldata, relidx, &mem.rel);
+                 if (r == NULL)
+                   INTERNAL_ERROR (fname);
                  offset = r->r_offset;
                  addend = 0;
                  rtype = GELF_R_TYPE (r->r_info);
@@ -685,6 +691,8 @@ remove_debug_relocations (Ebl *ebl, Elf *elf, GElf_Ehdr *ehdr,
              GElf_Sym *sym = gelf_getsymshndx (symdata, xndxdata,
                                                symndx, &sym_mem,
                                                  &xndx);
+             if (sym == NULL)
+               INTERNAL_ERROR (fname);
              Elf32_Word sec = (sym->st_shndx == SHN_XINDEX
                                ? xndx : sym->st_shndx);