elfcmp: Add some NULL and zero checks.

https://bugzilla.redhat.com/show_bug.cgi?id=1170810#c17

Reported-by: Alexander Cherepanov <cherepan@mccme.ru>
Signed-off-by: Mark Wielaard <mjw@redhat.com>

diff --git a/src/ChangeLog b/src/ChangeLog
index 5adf07d..dad984e 100644 (file)
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2015-01-03  Mark Wielaard  <mjw@redhat.com>
+
+       * elfcmp (main): Check section name is not NULL. Check sh_entsize
+       is not zero for symbol tables. Check phdrs are not NULL.
+       (search_for_copy_reloc): Check sh_entsize is not zero.
+
 2014-12-30  Mark Wielaard  <mjw@redhat.com>
 
        * elflint.c (check_scn_group): Check d_buf and name are not NULL.

diff --git a/src/elfcmp.c b/src/elfcmp.c
index d1008b3..f8a4572 100644 (file)
--- a/src/elfcmp.c
+++ b/src/elfcmp.c
@@ -287,7 +287,8 @@ main (int argc, char *argv[])
 
       /* Compare the headers.  We allow the name to be at a different
         location.  */
-      if (unlikely (strcmp (sname1, sname2) != 0))
+      if (unlikely (sname1 == NULL || sname2 == NULL
+                   || strcmp (sname1, sname2) != 0))
        {
          error (0, 0, gettext ("%s %s differ: section [%zu], [%zu] name"),
                 fname1, fname2, elf_ndxscn (scn1), elf_ndxscn (scn2));
@@ -295,8 +296,8 @@ main (int argc, char *argv[])
        }
 
       /* We ignore certain sections.  */
-      if (strcmp (sname1, ".gnu_debuglink") == 0
-         || strcmp (sname1, ".gnu.prelink_undo") == 0)
+      if ((sname1 != NULL && strcmp (sname1, ".gnu_debuglink") == 0)
+         || (sname1 != NULL && strcmp (sname1, ".gnu.prelink_undo") == 0))
        continue;
 
       if (shdr1->sh_type != shdr2->sh_type
@@ -333,6 +334,11 @@ main (int argc, char *argv[])
        {
        case SHT_DYNSYM:
        case SHT_SYMTAB:
+         if (shdr1->sh_entsize == 0)
+           error (2, 0,
+                  gettext ("symbol table [%zu] in '%s' has zero sh_entsize"),
+                  elf_ndxscn (scn1), fname1);
+
          /* Iterate over the symbol table.  We ignore the st_size
             value of undefined symbols.  */
          for (int ndx = 0; ndx < (int) (shdr1->sh_size / shdr1->sh_entsize);
@@ -591,13 +597,13 @@ cannot read note section [%zu] '%s' in '%s': %s"),
     {
       GElf_Phdr phdr1_mem;
       GElf_Phdr *phdr1 = gelf_getphdr (elf1, ndx, &phdr1_mem);
-      if (ehdr1 == NULL)
+      if (phdr1 == NULL)
        error (2, 0,
               gettext ("cannot get program header entry %d of '%s': %s"),
               ndx, fname1, elf_errmsg (-1));
       GElf_Phdr phdr2_mem;
       GElf_Phdr *phdr2 = gelf_getphdr (elf2, ndx, &phdr2_mem);
-      if (ehdr2 == NULL)
+      if (phdr2 == NULL)
        error (2, 0,
               gettext ("cannot get program header entry %d of '%s': %s"),
               ndx, fname2, elf_errmsg (-1));
@@ -760,7 +766,7 @@ search_for_copy_reloc (Ebl *ebl, size_t scnndx, int symndx)
               gettext ("cannot get content of section %zu: %s"),
               elf_ndxscn (scn), elf_errmsg (-1));
 
-      if (shdr->sh_type == SHT_REL)
+      if (shdr->sh_type == SHT_REL && shdr->sh_entsize != 0)
        for (int ndx = 0; ndx < (int) (shdr->sh_size / shdr->sh_entsize);
             ++ndx)
          {
@@ -774,7 +780,7 @@ search_for_copy_reloc (Ebl *ebl, size_t scnndx, int symndx)
                && ebl_copy_reloc_p (ebl, GELF_R_TYPE (rel->r_info)))
              return true;
          }
-      else
+      else if (shdr->sh_entsize != 0)
        for (int ndx = 0; ndx < (int) (shdr->sh_size / shdr->sh_entsize);
             ++ndx)
          {