Use elf_getphdrnum instead of accessing ehdr->e_phnum directly.

Using elf_getphdrnum lets us handle ELF files that use more than PN_XNUM
phdrs. And guards against some corrupt files.

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

7 files changed, 56 insertions, 27 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index bab948a1..bace91d5 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,15 @@
+2014-11-22  Mark Wielaard  <[email protected]>
+
+	* elflint.c (check_sections): Call ebl_bss_plt_p without ehdr.
+	* findtextrel.c (process_file): Use elf_getphdrnum.
+	* readelf.c (process_elf_file): Remove redundant ehdr->e_phoff check.
+	(print_phdr): Check phnum.
+	* size.c (show_segments): Use elf_getphdrnum.
+	* strip.c (handle_elf): Likewise.
+	* unstrip.c (copy_elf): Likewise.
+	(copy_elided_sections): Likewise.
+	(handle_file): Likewise.
+
 2014-11-18  Mark Wielaard  <[email protected]>
 
 	* readelf.c (print_cfa_program): Fix sanity check of DW_FORM_block
diff --git a/src/elflint.c b/src/elflint.c
index d6a47748..fbc78ede 100644
--- a/src/elflint.c
+++ b/src/elflint.c
@@ -3532,7 +3532,7 @@ cannot get section header for section [%2zu] '%s': %s\n"),
 
 		GElf_Word good_type = special_sections[s].type;
 		if (IS_KNOWN_SPECIAL (s, ".plt", false)
-		    && ebl_bss_plt_p (ebl, ehdr))
+		    && ebl_bss_plt_p (ebl))
 		  good_type = SHT_NOBITS;
 
 		/* In a debuginfo file, any normal section can be SHT_NOBITS.
diff --git a/src/findtextrel.c b/src/findtextrel.c
index 9fd81633..264a06bd 100644
--- a/src/findtextrel.c
+++ b/src/findtextrel.c
@@ -1,5 +1,5 @@
 /* Locate source files or functions which caused text relocations.
-   Copyright (C) 2005-2010, 2012 Red Hat, Inc.
+   Copyright (C) 2005-2010, 2012, 2014 Red Hat, Inc.
    This file is part of elfutils.
    Written by Ulrich Drepper <[email protected]>, 2005.
 
@@ -324,14 +324,20 @@ process_file (const char *fname, bool more_than_one)
   if (segments == NULL)
     error (1, errno, gettext ("while reading ELF file"));
 
-  for (int i = 0; i < ehdr->e_phnum; ++i)
+  size_t phnum;
+  if (elf_getphdrnum (elf, &phnum) != 0)
+    error (1, 0, gettext ("cannot get program header count: %s"),
+           elf_errmsg (-1));
+
+
+  for (size_t i = 0; i < phnum; ++i)
     {
       GElf_Phdr phdr_mem;
       GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem);
       if (phdr == NULL)
 	{
 	  error (0, 0,
-		 gettext ("cannot get program header index at offset %d: %s"),
+		 gettext ("cannot get program header index at offset %zd: %s"),
 		 i, elf_errmsg (-1));
 	  result = 1;
 	  goto next;
@@ -349,7 +355,7 @@ process_file (const char *fname, bool more_than_one)
 	      if (segments == NULL)
 		{
 		  error (0, 0, gettext ("\
-cannot get program header index at offset %d: %s"),
+cannot get program header index at offset %zd: %s"),
 			 i, elf_errmsg (-1));
 		  result = 1;
 		  goto next;
diff --git a/src/readelf.c b/src/readelf.c
index 08de7989..3b1f035a 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -835,11 +835,6 @@ process_elf_file (Dwfl_Module *dwflmod, int fd)
 	   gettext ("cannot determine number of program headers: %s"),
 	   elf_errmsg (-1));
 
-  /* If there isn't actually a program header then set phnum to zero.
-     Don't do any extra work.  gelf_getphdr will always return NULL.  */
-  if (ehdr->e_phoff == 0)
-    phnum = 0;
-
   /* For an ET_REL file, libdwfl has adjusted the in-core shdrs
      and may have applied relocation to some sections.
      So we need to get a fresh Elf handle on the file to display those.  */
@@ -1162,7 +1157,7 @@ There are %d section headers, starting at offset %#" PRIx64 ":\n\
 static void
 print_phdr (Ebl *ebl, GElf_Ehdr *ehdr)
 {
-  if (ehdr->e_phnum == 0 || ehdr->e_phoff == 0)
+  if (phnum == 0)
     /* No program header, this is OK in relocatable objects.  */
     return;
 
diff --git a/src/size.c b/src/size.c
index cb67999b..0e7e41e4 100644
--- a/src/size.c
+++ b/src/size.c
@@ -600,14 +600,13 @@ show_bsd_totals (void)
 static void
 show_segments (Elf *elf, const char *fullname)
 {
-  GElf_Ehdr ehdr_mem;
-  GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem);
-  if (ehdr == NULL)
+  size_t phnum;
+  if (elf_getphdrnum (elf, &phnum) != 0)
     INTERNAL_ERROR (fullname);
 
   GElf_Off total = 0;
   bool first = true;
-  for (size_t cnt = 0; cnt < ehdr->e_phnum; ++cnt)
+  for (size_t cnt = 0; cnt < phnum; ++cnt)
     {
       GElf_Phdr phdr_mem;
       GElf_Phdr *phdr;
diff --git a/src/strip.c b/src/strip.c
index c9a1d8df..2b217996 100644
--- a/src/strip.c
+++ b/src/strip.c
@@ -502,6 +502,11 @@ handle_elf (int fd, Elf *elf, const char *prefix, const char *fname,
     error (EXIT_FAILURE, 0,
 	   gettext ("cannot get section header string table index"));
 
+  /* Get the number of phdrs in the old file.  */
+  size_t phnum;
+  if (elf_getphdrnum (elf, &phnum) != 0)
+    error (EXIT_FAILURE, 0, gettext ("cannot get number of phdrs"));
+
   /* We now create a new ELF descriptor for the same file.  We
      construct it almost exactly in the same way with some information
      dropped.  */
@@ -513,7 +518,7 @@ handle_elf (int fd, Elf *elf, const char *prefix, const char *fname,
 
   if (unlikely (gelf_newehdr (newelf, gelf_getclass (elf)) == 0)
       || (ehdr->e_type != ET_REL
-	  && unlikely (gelf_newphdr (newelf, ehdr->e_phnum) == 0)))
+	  && unlikely (gelf_newphdr (newelf, phnum) == 0)))
     {
       error (0, 0, gettext ("cannot create new file '%s': %s"),
 	     output_fname, elf_errmsg (-1));
@@ -522,7 +527,7 @@ handle_elf (int fd, Elf *elf, const char *prefix, const char *fname,
 
   /* Copy over the old program header if needed.  */
   if (ehdr->e_type != ET_REL)
-    for (cnt = 0; cnt < ehdr->e_phnum; ++cnt)
+    for (cnt = 0; cnt < phnum; ++cnt)
       {
 	GElf_Phdr phdr_mem;
 	GElf_Phdr *phdr = gelf_getphdr (elf, cnt, &phdr_mem);
@@ -537,7 +542,7 @@ handle_elf (int fd, Elf *elf, const char *prefix, const char *fname,
       debugelf = elf_begin (debug_fd, ELF_C_WRITE_MMAP, NULL);
       if (unlikely (gelf_newehdr (debugelf, gelf_getclass (elf)) == 0)
 	  || (ehdr->e_type != ET_REL
-	      && unlikely (gelf_newphdr (debugelf, ehdr->e_phnum) == 0)))
+	      && unlikely (gelf_newphdr (debugelf, phnum) == 0)))
 	{
 	  error (0, 0, gettext ("cannot create new file '%s': %s"),
 		 debug_fname, elf_errmsg (-1));
@@ -546,7 +551,7 @@ handle_elf (int fd, Elf *elf, const char *prefix, const char *fname,
 
       /* Copy over the old program header if needed.  */
       if (ehdr->e_type != ET_REL)
-	for (cnt = 0; cnt < ehdr->e_phnum; ++cnt)
+	for (cnt = 0; cnt < phnum; ++cnt)
 	  {
 	    GElf_Phdr phdr_mem;
 	    GElf_Phdr *phdr = gelf_getphdr (elf, cnt, &phdr_mem);
diff --git a/src/unstrip.c b/src/unstrip.c
index f6af4500..989ac5ff 100644
--- a/src/unstrip.c
+++ b/src/unstrip.c
@@ -241,7 +241,7 @@ warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
 #define ELF_CHECK(call, msg)						      \
   do									      \
     {									      \
-      if (!(call)) 							      \
+      if (unlikely (!(call)))						      \
 	error (EXIT_FAILURE, 0, msg, elf_errmsg (-1));			      \
     } while (0)
 
@@ -257,13 +257,17 @@ copy_elf (Elf *outelf, Elf *inelf)
   ELF_CHECK (gelf_update_ehdr (outelf, ehdr),
 	     _("cannot copy ELF header: %s"));
 
-  if (ehdr->e_phnum > 0)
+  size_t phnum;
+  ELF_CHECK (elf_getphdrnum (inelf, &phnum) == 0,
+	     _("cannot get number of program headers: %s"));
+
+  if (phnum > 0)
     {
-      ELF_CHECK (gelf_newphdr (outelf, ehdr->e_phnum),
+      ELF_CHECK (gelf_newphdr (outelf, phnum),
 		 _("cannot create program headers: %s"));
 
       GElf_Phdr phdr_mem;
-      for (uint_fast16_t i = 0; i < ehdr->e_phnum; ++i)
+      for (size_t i = 0; i < phnum; ++i)
 	ELF_CHECK (gelf_update_phdr (outelf, i,
 				     gelf_getphdr (inelf, i, &phdr_mem)),
 		   _("cannot copy program header: %s"));
@@ -1823,12 +1827,16 @@ more sections in stripped file than debug file -- arguments reversed?"));
     }
   while (skip_reloc);
 
-  if (stripped_ehdr->e_phnum > 0)
-    ELF_CHECK (gelf_newphdr (unstripped, stripped_ehdr->e_phnum),
+  size_t phnum;
+  ELF_CHECK (elf_getphdrnum (stripped, &phnum) == 0,
+	     _("cannot get number of program headers: %s"));
+
+  if (phnum > 0)
+    ELF_CHECK (gelf_newphdr (unstripped, phnum),
 	       _("cannot create program headers: %s"));
 
   /* Copy each program header from the stripped file.  */
-  for (uint_fast16_t i = 0; i < stripped_ehdr->e_phnum; ++i)
+  for (size_t i = 0; i < phnum; ++i)
     {
       GElf_Phdr phdr_mem;
       GElf_Phdr *phdr = gelf_getphdr (stripped, i, &phdr_mem);
@@ -1863,11 +1871,15 @@ handle_file (const char *output_file, bool create_dirs,
 	     Elf *stripped, const GElf_Ehdr *stripped_ehdr,
 	     Elf *unstripped)
 {
+  size_t phnum;
+  ELF_CHECK (elf_getphdrnum (stripped, &phnum) == 0,
+	     _("cannot get number of program headers: %s"));
+
   /* Determine the address bias between the debuginfo file and the main
      file, which may have been modified by prelinking.  */
   GElf_Addr bias = 0;
   if (unstripped != NULL)
-    for (uint_fast16_t i = 0; i < stripped_ehdr->e_phnum; ++i)
+    for (size_t i = 0; i < phnum; ++i)
       {
 	GElf_Phdr phdr_mem;
 	GElf_Phdr *phdr = gelf_getphdr (stripped, i, &phdr_mem);