Check elf_strptr didn't fail getting section name.

Since elf_strptr can fail and return NULL we should always check the result
before usage. Debug sections are only handled by section name, so make sure
the name actually exists.

Signed-off-by: Mark Wielaard <[email protected]>

10 files changed, 41 insertions, 19 deletions

diff --git a/backends/ChangeLog b/backends/ChangeLog
index 82a2bf15..abd22bf8 100644
--- a/backends/ChangeLog
+++ b/backends/ChangeLog
@@ -1,3 +1,7 @@
+2014-11-17  Mark Wielaard  <[email protected]>
+
+	* ppc64_init.c (ppc64_init): Check section name is not NULL.
+
 2014-10-06  Mark Wielaard  <[email protected]>
 
 	* libebl_CPU.h (dwarf_peel_type): Removed.
diff --git a/backends/ppc64_init.c b/backends/ppc64_init.c
index 7ea2b236..56e1828e 100644
--- a/backends/ppc64_init.c
+++ b/backends/ppc64_init.c
@@ -90,13 +90,16 @@ ppc64_init (elf, machine, eh, ehlen)
 	      if (opd_shdr != NULL
 		  && (opd_shdr->sh_flags & SHF_ALLOC) != 0
 		  && opd_shdr->sh_type == SHT_PROGBITS
-		  && opd_shdr->sh_size > 0
-		  && strcmp (elf_strptr (elf, ehdr->e_shstrndx,
-					 opd_shdr->sh_name), ".opd") == 0)
+		  && opd_shdr->sh_size > 0)
 		{
-		  eh->fd_addr = opd_shdr->sh_addr;
-		  eh->fd_data = elf_getdata (scn, NULL);
-		  break;
+		  const char *name = elf_strptr (elf, ehdr->e_shstrndx,
+						 opd_shdr->sh_name);
+		  if (name != NULL && strcmp (name, ".opd") == 0)
+		    {
+		      eh->fd_addr = opd_shdr->sh_addr;
+		      eh->fd_data = elf_getdata (scn, NULL);
+		      break;
+		    }
 		}
 	    }
 	}
diff --git a/libebl/ChangeLog b/libebl/ChangeLog
index 5ec71016..b6a0e632 100644
--- a/libebl/ChangeLog
+++ b/libebl/ChangeLog
@@ -1,3 +1,7 @@
+2014-11-17  Mark Wielaard  <[email protected]>
+
+	* ebldebugscnp.c (ebl_debugscn_p): Check name is not NULL.
+
 2014-06-17  Mark Wielaard  <[email protected]>
 
 	* eblinitreg.c (ebl_func_addr_mask): New function.
diff --git a/libebl/ebldebugscnp.c b/libebl/ebldebugscnp.c
index f2351e23..01a56754 100644
--- a/libebl/ebldebugscnp.c
+++ b/libebl/ebldebugscnp.c
@@ -1,5 +1,5 @@
 /* Check section name for being that of a debug informatino section.
-   Copyright (C) 2002 Red Hat, Inc.
+   Copyright (C) 2002, 2014 Red Hat, Inc.
    This file is part of elfutils.
    Written by Ulrich Drepper <[email protected]>, 2002.
 
@@ -40,5 +40,5 @@ ebl_debugscn_p (ebl, name)
      Ebl *ebl;
      const char *name;
 {
-  return ebl->debugscn_p (name);
+  return name != NULL && ebl->debugscn_p (name);
 }
diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index 633a8923..9ae24a9b 100644
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -1,3 +1,7 @@
+2014-11-17  Mark Wielaard  <[email protected]>
+
+	* elf-knowledge.h (SECTION_STRIP_P): Check name is not NULL.
+
 2014-11-16  Mark Wielaard  <[email protected]>
 
 	* elf_getshdrstrndx.c: Check there are section headers before
diff --git a/libelf/elf-knowledge.h b/libelf/elf-knowledge.h
index 99fb9107..24534b38 100644
--- a/libelf/elf-knowledge.h
+++ b/libelf/elf-knowledge.h
@@ -1,5 +1,5 @@
 /* Accumulation of various pieces of knowledge about ELF.
-   Copyright (C) 2000-2012 Red Hat, Inc.
+   Copyright (C) 2000-2012, 2014 Red Hat, Inc.
    This file is part of elfutils.
    Written by Ulrich Drepper <[email protected]>, 2000.
 
@@ -41,7 +41,8 @@
    && (shdr)->sh_type != SHT_NOTE					      \
    && (((shdr)->sh_type) != SHT_PROGBITS				      \
        /* Never remove .gnu.warning.* sections.  */			      \
-       || (strncmp (name, ".gnu.warning.", sizeof ".gnu.warning." - 1) != 0   \
+       || (name != NULL							      \
+	   && strncmp (name, ".gnu.warning.", sizeof ".gnu.warning." - 1) != 0\
 	   /* We remove .comment sections only if explicitly told to do so. */\
 	   && (remove_comment						      \
 	       || strcmp (name, ".comment") != 0))))
diff --git a/src/ChangeLog b/src/ChangeLog
index 96f21fdc..727d1001 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,11 @@
 2014-11-17  Mark Wielaard  <[email protected]>
 
+	* elfcmp.c (main): Check section names are NULL before use.
+	* objdump.c (section_match): Likewise.
+	* size.c (show_sysv): Likewise.
+
+2014-11-17  Mark Wielaard  <[email protected]>
+
 	* readelf.c (print_debug_frame_section): Warn if ptr_size is not 4
 	or 8 instead of just calling print_cfa_program.
 
diff --git a/src/elfcmp.c b/src/elfcmp.c
index 2d85f0b2..c420019f 100644
--- a/src/elfcmp.c
+++ b/src/elfcmp.c
@@ -1,5 +1,5 @@
 /* Compare relevant content of two ELF files.
-   Copyright (C) 2005-2012 Red Hat, Inc.
+   Copyright (C) 2005-2012, 2014 Red Hat, Inc.
    This file is part of elfutils.
    Written by Ulrich Drepper <[email protected]>, 2005.
 
@@ -355,7 +355,8 @@ main (int argc, char *argv[])
 					      sym1->st_name);
 	      const char *name2 = elf_strptr (elf2, shdr2->sh_link,
 					      sym2->st_name);
-	      if (unlikely (strcmp (name1, name2) != 0
+	      if (unlikely (name1 == NULL || name2 == NULL
+			    || strcmp (name1, name2) != 0
 			    || sym1->st_value != sym2->st_value
 			    || (sym1->st_size != sym2->st_size
 				&& sym1->st_shndx != SHN_UNDEF)
diff --git a/src/objdump.c b/src/objdump.c
index ebad25d5..5376447a 100644
--- a/src/objdump.c
+++ b/src/objdump.c
@@ -1,5 +1,5 @@
 /* Print information from ELF file in human-readable form.
-   Copyright (C) 2005, 2006, 2007, 2009, 2011, 2012 Red Hat, Inc.
+   Copyright (C) 2005, 2006, 2007, 2009, 2011, 2012, 2014 Red Hat, Inc.
    This file is part of elfutils.
    Written by Ulrich Drepper <[email protected]>, 2005.
 
@@ -460,13 +460,13 @@ section_match (Elf *elf, uint32_t scnndx, GElf_Shdr *shdr, size_t shstrndx)
     return true;
 
   struct section_list *runp = section_list;
+  const char *name = elf_strptr (elf, shstrndx, shdr->sh_name);
 
   do
     {
       if (runp->is_name)
 	{
-	  if (strcmp (runp->name,
-		      elf_strptr (elf, shstrndx, shdr->sh_name)) == 0)
+	  if (name && strcmp (runp->name, name) == 0)
 	    return true;
 	}
       else
diff --git a/src/size.c b/src/size.c
index 9db55c80..cb67999b 100644
--- a/src/size.c
+++ b/src/size.c
@@ -427,10 +427,9 @@ show_sysv (Elf *elf, const char *prefix, const char *fname,
 	INTERNAL_ERROR (fullname);
 
       /* Ignore all sections which are not used at runtime.  */
-      if ((shdr->sh_flags & SHF_ALLOC) != 0)
-	maxlen = MAX (maxlen,
-		      (int) strlen (elf_strptr (elf, shstrndx,
-						shdr->sh_name)));
+      const char *name = elf_strptr (elf, shstrndx, shdr->sh_name);
+      if (name != NULL && (shdr->sh_flags & SHF_ALLOC) != 0)
+	maxlen = MAX (maxlen, (int) strlen (name));
     }
 
   fputs_unlocked (fname, stdout);