[PATCH] Fix some potential deref-of-null error

[Maks Mishin]

strip.c: Pointer `arhdr` created at strip.c:2741 and then dereferenced without 
NULL-check.
The same situation for the `arhdr` pointer at the objdump.c:313 and
the `h` pointer at the readelf.c:13545.

Triggers found by static analyzer Svace.

Signed-off-by: Maks Mishin <maks.mishi...@gmail.com>
---
 src/objdump.c | 5 +++++
 src/readelf.c | 5 +++++
 src/strip.c   | 5 +++++
 3 files changed, 15 insertions(+)

diff --git a/src/objdump.c b/src/objdump.c
index d43c1dd6..8ad8cdb5 100644
--- a/src/objdump.c
+++ b/src/objdump.c
@@ -311,6 +311,11 @@ handle_ar (int fd, Elf *elf, const char *prefix, const 
char *fname,
     {
       /* The the header for this element.  */
       Elf_Arhdr *arhdr = elf_getarhdr (subelf);
+      if (arhdr == NULL)
+       {
+         printf ("cannot get arhdr: %s\n", elf_errmsg (-1));
+         exit (1);
+       }
 
       /* Skip over the index entries.  */
       if (strcmp (arhdr->ar_name, "/") != 0
diff --git a/src/readelf.c b/src/readelf.c
index 48035264..96d7877c 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -13543,6 +13543,11 @@ dump_archive_index (Elf *elf, const char *fname)
                          as_off, fname, elf_errmsg (-1));
 
          const Elf_Arhdr *h = elf_getarhdr (subelf);
+         if (h == NULL)
+       {
+         printf ("cannot get arhdr: %s\n", elf_errmsg (-1));
+         exit (1);
+       }
 
          printf (_("Archive member '%s' contains:\n"), h->ar_name);
 
diff --git a/src/strip.c b/src/strip.c
index 403e0f6f..44389c9b 100644
--- a/src/strip.c
+++ b/src/strip.c
@@ -2739,6 +2739,11 @@ handle_ar (int fd, Elf *elf, const char *prefix, const 
char *fname,
     {
       /* The the header for this element.  */
       Elf_Arhdr *arhdr = elf_getarhdr (subelf);
+         if (arhdr == NULL)
+       {
+         printf ("cannot get arhdr: %s\n", elf_errmsg (-1));
+         exit (1);
+       }
 
       if (elf_kind (subelf) == ELF_K_ELF)
        result |= handle_elf (fd, subelf, new_prefix, arhdr->ar_name, 0, NULL);
-- 
2.30.2