[Emacs-diffs] /srv/bzr/emacs/trunk r112469: * unexelf.c: Fix some 32-bit integer problems, notably when debugging.

[Paul Eggert]

------------------------------------------------------------
revno: 112469
author: Paul Eggert  <address@hidden>
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Sun 2013-05-05 21:52:00 -0700
message:
  * unexelf.c: Fix some 32-bit integer problems, notably when debugging.
  
  Include <limits.h>, <stdbool.h>, <intprops.h>, <verify.h>.
  Verify that ElfW (Half) fits in int.
  (fatal): Use same signature as lisp.h.
  (UNEXELF_DEBUG): New macro, replacing DEBUG, so that people can
  configure and build with -DUNEXELF_DEBUG without worrying about
  other modules that use DEBUG.
  (DEBUG_LOG) [UNEXELF_DEBUG]: New macro.  All debug code that prints
  possibly-wide integers now uses it instead of plain fprintf.
  (entry_address): New function, which avoids problems with 32-bit
  overflow on 64-bit hosts.
  (OLD_SECTION_H, NEW_SECTION_H, NEW_PROGRAM_H): Use it.
  (round_up): Don't assume the remainder fits in int.
  (find_section): Use bool for boolean.  Simplify debug code.
  (unexec): Don't assume file sizes fit in int or size_t.
  Omit unnecessary trailing newline in 'fatal' format.
  Use strerror rather than outputting decimal error number.
  Remove unused code when emacs is not defined;
  this file relies on Emacs now.
  Don't assume e_phnum and e_shnum are positive.
modified:
  src/ChangeLog
  src/unexelf.c

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2013-05-06 04:31:16 +0000
+++ b/src/ChangeLog     2013-05-06 04:52:00 +0000
@@ -1,5 +1,26 @@
 2013-05-06  Paul Eggert  <address@hidden>
 
+       * unexelf.c: Fix some 32-bit integer problems, notably when debugging.
+       Include <limits.h>, <stdbool.h>, <intprops.h>, <verify.h>.
+       Verify that ElfW (Half) fits in int.
+       (fatal): Use same signature as lisp.h.
+       (UNEXELF_DEBUG): New macro, replacing DEBUG, so that people can
+       configure and build with -DUNEXELF_DEBUG without worrying about
+       other modules that use DEBUG.
+       (DEBUG_LOG) [UNEXELF_DEBUG]: New macro.  All debug code that prints
+       possibly-wide integers now uses it instead of plain fprintf.
+       (entry_address): New function, which avoids problems with 32-bit
+       overflow on 64-bit hosts.
+       (OLD_SECTION_H, NEW_SECTION_H, NEW_PROGRAM_H): Use it.
+       (round_up): Don't assume the remainder fits in int.
+       (find_section): Use bool for boolean.  Simplify debug code.
+       (unexec): Don't assume file sizes fit in int or size_t.
+       Omit unnecessary trailing newline in 'fatal' format.
+       Use strerror rather than outputting decimal error number.
+       Remove unused code when emacs is not defined;
+       this file relies on Emacs now.
+       Don't assume e_phnum and e_shnum are positive.
+
        * regex.c: Fix problems when DEBUG is defined.
        (extract_number, extract_number_and_incr): Define regardless of
        whether DEBUG is defined; that's simpler and makes the code less

=== modified file 'src/unexelf.c'
--- a/src/unexelf.c     2013-01-01 09:11:05 +0000
+++ b/src/unexelf.c     2013-05-06 04:52:00 +0000
@@ -388,16 +388,19 @@
 #include <config.h>
 #include <unexec.h>
 
-extern void fatal (const char *msgid, ...);
+extern _Noreturn void fatal (const char *, ...) ATTRIBUTE_FORMAT_PRINTF (1, 2);
 
-#include <sys/types.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <memory.h>
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <sys/stat.h>
-#include <memory.h>
-#include <errno.h>
+#include <sys/types.h>
 #include <unistd.h>
-#include <fcntl.h>
+
 #if !defined (__NetBSD__) && !defined (__OpenBSD__)
 #include <elf.h>
 #endif /* not __NetBSD__ and not __OpenBSD__ */
@@ -519,6 +522,17 @@
 # define ElfW(type) ElfExpandBitsW (ELFSIZE, type)
 #endif
 
+/* The code often converts ElfW (Half) values like e_shentsize to int;
+   check that this doesn't lose information.  */
+#include <intprops.h>
+#include <verify.h>
+verify ((! TYPE_SIGNED (ElfW (Half)) || INT_MIN <= TYPE_MINIMUM (ElfW (Half)))
+       && TYPE_MAXIMUM (ElfW (Half)) <= INT_MAX);
+
+#ifdef UNEXELF_DEBUG
+# define DEBUG_LOG(expr) fprintf (stderr, #expr " 0x%jx\n", (uintmax_t) (expr))
+#endif
+
 /* Get the address of a particular section or program header entry,
  * accounting for the size of the entries.
  */
@@ -546,17 +560,25 @@
    Apr 23, 1996
    */
 
+static void *
+entry_address (void *section_h, int idx, int num, int entsize)
+{
+  char *h = section_h;
+  ptrdiff_t n = idx;
+  return h + entsize * n;
+}
+
 #define OLD_SECTION_H(n) \
-     (*(ElfW (Shdr) *) ((byte *) old_section_h + old_file_h->e_shentsize * 
(n)))
+  (*(ElfW (Shdr) *) entry_address (old_section_h, n, old_file_h->e_shnum, \
+                                  old_file_h->e_shentsize))
 #define NEW_SECTION_H(n) \
-     (*(ElfW (Shdr) *) ((byte *) new_section_h + new_file_h->e_shentsize * 
(n)))
+  (*(ElfW (Shdr) *) entry_address (new_section_h, n, new_file_h->e_shnum, \
+                                  new_file_h->e_shentsize))
 #define NEW_PROGRAM_H(n) \
-     (*(ElfW (Phdr) *) ((byte *) new_program_h + new_file_h->e_phentsize * 
(n)))
+  (*(ElfW (Phdr) *) entry_address (new_program_h, n, new_file_h->e_phnum, \
+                                  new_file_h->e_phentsize))
 
-#define PATCH_INDEX(n) \
-  do { \
-        if ((int) (n) >= old_bss_index) \
-          (n)++; } while (0)
+#define PATCH_INDEX(n) ((n) += old_bss_index <= (n))
 typedef unsigned char byte;
 
 /* Round X up to a multiple of Y.  */
@@ -564,7 +586,7 @@
 static ElfW (Addr)
 round_up (ElfW (Addr) x, ElfW (Addr) y)
 {
-  int rem = x % y;
+  ElfW (Addr) rem = x % y;
   if (rem == 0)
     return x;
   return x - rem + y;
@@ -575,33 +597,28 @@
    about the file we are looking in.
 
    If we don't find the section NAME, that is a fatal error
-   if NOERROR is 0; we return -1 if NOERROR is nonzero.  */
+   if NOERROR is false; return -1 if NOERROR is true.  */
 
 static int
 find_section (const char *name, const char *section_names, const char 
*file_name,
-             ElfW (Ehdr) *old_file_h, ElfW (Shdr) *old_section_h, int noerror)
+             ElfW (Ehdr) *old_file_h, ElfW (Shdr) *old_section_h,
+             bool noerror)
 {
   int idx;
 
   for (idx = 1; idx < old_file_h->e_shnum; idx++)
     {
-#ifdef DEBUG
-      fprintf (stderr, "Looking for %s - found %s\n", name,
-              section_names + OLD_SECTION_H (idx).sh_name);
+      char const *found_name = section_names + OLD_SECTION_H (idx).sh_name;
+#ifdef UNEXELF_DEBUG
+      fprintf (stderr, "Looking for %s - found %s\n", name, found_name);
 #endif
-      if (!strcmp (section_names + OLD_SECTION_H (idx).sh_name,
-                  name))
-       break;
-    }
-  if (idx == old_file_h->e_shnum)
-    {
-      if (noerror)
-       return -1;
-      else
-       fatal ("Can't find %s in %s.\n", name, file_name);
+      if (strcmp (name, found_name) == 0)
+       return idx;
     }
 
-  return idx;
+  if (! noerror)
+    fatal ("Can't find %s in %s", name, file_name);
+  return -1;
 }
 
 /* ****************************************************************
@@ -616,11 +633,9 @@
 void
 unexec (const char *new_name, const char *old_name)
 {
-  int new_file, old_file, new_file_size;
-
-#if defined (emacs) || !defined (DEBUG)
+  int new_file, old_file;
+  off_t new_file_size;
   void *new_break;
-#endif
 
   /* Pointers to the base of the image of the two files.  */
   caddr_t old_base, new_base;
@@ -654,7 +669,7 @@
   int old_mdebug_index;
 #endif
   struct stat stat_buf;
-  int old_file_size;
+  off_t old_file_size;
 
   /* Open the old file, allocate a buffer of the right size, and read
      in the file contents.  */
@@ -662,15 +677,15 @@
   old_file = open (old_name, O_RDONLY);
 
   if (old_file < 0)
-    fatal ("Can't open %s for reading: errno %d\n", old_name, errno);
+    fatal ("Can't open %s for reading: %s", old_name, strerror (errno));
 
-  if (fstat (old_file, &stat_buf) == -1)
-    fatal ("Can't fstat (%s): errno %d\n", old_name, errno);
+  if (fstat (old_file, &stat_buf) != 0)
+    fatal ("Can't fstat (%s): %s", old_name, strerror (errno));
 
 #if MAP_ANON == 0
   mmap_fd = open ("/dev/zero", O_RDONLY);
   if (mmap_fd < 0)
-    fatal ("Can't open /dev/zero for reading: errno %d\n", errno, 0);
+    fatal ("Can't open /dev/zero for reading: %s", strerror (errno));
 #endif
 
   /* We cannot use malloc here because that may use sbrk.  If it does,
@@ -678,13 +693,15 @@
      extra careful to use the correct value of sbrk(0) after
      allocating all buffers in the code below, which we aren't.  */
   old_file_size = stat_buf.st_size;
+  if (! (0 <= old_file_size && old_file_size <= SIZE_MAX))
+    fatal ("File size out of range");
   old_base = mmap (NULL, old_file_size, PROT_READ | PROT_WRITE,
                   MAP_ANON | MAP_PRIVATE, mmap_fd, 0);
   if (old_base == MAP_FAILED)
-    fatal ("Can't allocate buffer for %s\n", old_name, 0);
+    fatal ("Can't allocate buffer for %s: %s", old_name, strerror (errno));
 
-  if (read (old_file, old_base, stat_buf.st_size) != stat_buf.st_size)
-    fatal ("Didn't read all of %s: errno %d\n", old_name, errno);
+  if (read (old_file, old_base, old_file_size) != old_file_size)
+    fatal ("Didn't read all of %s: %s", old_name, strerror (errno));
 
   /* Get pointers to headers & section names */
 
@@ -755,12 +772,8 @@
   old_data_index = find_section (".data", old_section_names,
                                 old_name, old_file_h, old_section_h, 0);
 
-#if defined (emacs) || !defined (DEBUG)
   new_break = sbrk (0);
   new_bss_addr = (ElfW (Addr)) new_break;
-#else
-  new_bss_addr = old_bss_addr + old_bss_size + 0x1234;
-#endif
   new_data2_addr = old_bss_addr;
   new_data2_size = new_bss_addr - old_bss_addr;
   new_data2_offset = OLD_SECTION_H (old_data_index).sh_offset
@@ -771,38 +784,38 @@
      section) was unaligned.  */
   new_data2_incr = new_data2_size + (new_data2_offset - old_bss_offset);
 
-#ifdef DEBUG
+#ifdef UNEXELF_DEBUG
   fprintf (stderr, "old_bss_index %d\n", old_bss_index);
-  fprintf (stderr, "old_bss_addr %x\n", old_bss_addr);
-  fprintf (stderr, "old_bss_size %x\n", old_bss_size);
-  fprintf (stderr, "old_bss_offset %x\n", old_bss_offset);
-  fprintf (stderr, "new_bss_addr %x\n", new_bss_addr);
-  fprintf (stderr, "new_data2_addr %x\n", new_data2_addr);
-  fprintf (stderr, "new_data2_size %x\n", new_data2_size);
-  fprintf (stderr, "new_data2_offset %x\n", new_data2_offset);
-  fprintf (stderr, "new_data2_incr %x\n", new_data2_incr);
+  DEBUG_LOG (old_bss_addr);
+  DEBUG_LOG (old_bss_size);
+  DEBUG_LOG (old_bss_offset);
+  DEBUG_LOG (new_bss_addr);
+  DEBUG_LOG (new_data2_addr);
+  DEBUG_LOG (new_data2_size);
+  DEBUG_LOG (new_data2_offset);
+  DEBUG_LOG (new_data2_incr);
 #endif
 
-  if ((uintptr_t) new_bss_addr < (uintptr_t) old_bss_addr + old_bss_size)
-    fatal (".bss shrank when undumping???\n", 0, 0);
+  if (new_bss_addr < old_bss_addr + old_bss_size)
+    fatal (".bss shrank when undumping");
 
   /* Set the output file to the right size.  Allocate a buffer to hold
      the image of the new file.  Set pointers to various interesting
-     objects.  stat_buf still has old_file data.  */
+     objects.  */
 
   new_file = open (new_name, O_RDWR | O_CREAT, 0666);
   if (new_file < 0)
-    fatal ("Can't creat (%s): errno %d\n", new_name, errno);
+    fatal ("Can't creat (%s): %s", new_name, strerror (errno));
 
-  new_file_size = stat_buf.st_size + old_file_h->e_shentsize + new_data2_incr;
+  new_file_size = old_file_size + old_file_h->e_shentsize + new_data2_incr;
 
   if (ftruncate (new_file, new_file_size))
-    fatal ("Can't ftruncate (%s): errno %d\n", new_name, errno);
+    fatal ("Can't ftruncate (%s): %s", new_name, strerror (errno));
 
   new_base = mmap (NULL, new_file_size, PROT_READ | PROT_WRITE,
                   MAP_ANON | MAP_PRIVATE, mmap_fd, 0);
   if (new_base == MAP_FAILED)
-    fatal ("Can't allocate buffer for %s\n", old_name, 0);
+    fatal ("Can't allocate buffer for %s: %s", old_name, strerror (errno));
 
   new_file_h = (ElfW (Ehdr) *) new_base;
   new_program_h = (ElfW (Phdr) *) ((byte *) new_base + old_file_h->e_phoff);
@@ -825,10 +838,10 @@
   new_file_h->e_shoff += new_data2_incr;
   new_file_h->e_shnum += 1;
 
-#ifdef DEBUG
-  fprintf (stderr, "Old section offset %x\n", old_file_h->e_shoff);
+#ifdef UNEXELF_DEBUG
+  DEBUG_LOG (old_file_h->e_shoff);
   fprintf (stderr, "Old section count %d\n", old_file_h->e_shnum);
-  fprintf (stderr, "New section offset %x\n", new_file_h->e_shoff);
+  DEBUG_LOG (new_file_h->e_shoff);
   fprintf (stderr, "New section count %d\n", new_file_h->e_shnum);
 #endif
 
@@ -839,7 +852,7 @@
      to adjust the offset and address of any segment that is above
      data2, just in case we decide to allow this later.  */
 
-  for (n = new_file_h->e_phnum - 1; n >= 0; n--)
+  for (n = new_file_h->e_phnum; --n >= 0; )
     {
       /* Compute maximum of all requirements for alignment of section.  */
       ElfW (Word) alignment = (NEW_PROGRAM_H (n)).p_align;
@@ -857,7 +870,7 @@
          > (old_sbss_index == -1
             ? old_bss_addr
             : round_up (old_bss_addr, alignment)))
-         fatal ("Program segment above .bss in %s\n", old_name, 0);
+         fatal ("Program segment above .bss in %s", old_name);
 
       if (NEW_PROGRAM_H (n).p_type == PT_LOAD
          && (round_up ((NEW_PROGRAM_H (n)).p_vaddr
@@ -867,7 +880,7 @@
        break;
     }
   if (n < 0)
-    fatal ("Couldn't find segment next to .bss in %s\n", old_name, 0);
+    fatal ("Couldn't find segment next to .bss in %s", old_name);
 
   /* Make sure that the size includes any padding before the old .bss
      section.  */
@@ -875,7 +888,7 @@
   NEW_PROGRAM_H (n).p_memsz = NEW_PROGRAM_H (n).p_filesz;
 
 #if 0 /* Maybe allow section after data2 - does this ever happen? */
-  for (n = new_file_h->e_phnum - 1; n >= 0; n--)
+  for (n = new_file_h->e_phnum; --n >= 0; )
     {
       if (NEW_PROGRAM_H (n).p_vaddr
          && NEW_PROGRAM_H (n).p_vaddr >= new_data2_addr)
@@ -894,7 +907,7 @@
 
   /* Walk through all section headers, insert the new data2 section right
      before the new bss section. */
-  for (n = 1, nn = 1; n < (int) old_file_h->e_shnum; n++, nn++)
+  for (n = 1, nn = 1; n < old_file_h->e_shnum; n++, nn++)
     {
       caddr_t src;
       /* If it is (s)bss section, insert the new data2 section before it.  */
@@ -1173,7 +1186,7 @@
     }
 
   /* Update the symbol values of _edata and _end.  */
-  for (n = new_file_h->e_shnum - 1; n; n--)
+  for (n = new_file_h->e_shnum; 0 < --n; )
     {
       byte *symnames;
       ElfW (Sym) *symp, *symendp;
@@ -1233,7 +1246,7 @@
 
   /* This loop seeks out relocation sections for the data section, so
      that it can undo relocations performed by the runtime linker.  */
-  for (n = new_file_h->e_shnum - 1; n; n--)
+  for (n = new_file_h->e_shnum; 0 < --n; )
     {
       ElfW (Shdr) section = NEW_SECTION_H (n);
 
@@ -1293,8 +1306,8 @@
   /* Write out new_file, and free the buffers.  */
 
   if (write (new_file, new_base, new_file_size) != new_file_size)
-    fatal ("Didn't write %d bytes to %s: errno %d\n",
-          new_file_size, new_name, errno);
+    fatal ("Didn't write %lu bytes to %s: %s",
+          (unsigned long) new_file_size, new_name, strerror (errno));
   munmap (old_base, old_file_size);
   munmap (new_base, new_file_size);
 
@@ -1304,18 +1317,18 @@
   close (mmap_fd);
 #endif
 
-  if (close (old_file))
-    fatal ("Can't close (%s): errno %d\n", old_name, errno);
-
-  if (close (new_file))
-    fatal ("Can't close (%s): errno %d\n", new_name, errno);
-
-  if (stat (new_name, &stat_buf) == -1)
-    fatal ("Can't stat (%s): errno %d\n", new_name, errno);
+  if (close (old_file) != 0)
+    fatal ("Can't close (%s): %s", old_name, strerror (errno));
+
+  if (close (new_file) != 0)
+    fatal ("Can't close (%s): %s", new_name, strerror (errno));
+
+  if (stat (new_name, &stat_buf) != 0)
+    fatal ("Can't stat (%s): %s", new_name, strerror (errno));
 
   n = umask (777);
   umask (n);
   stat_buf.st_mode |= 0111 & ~n;
-  if (chmod (new_name, stat_buf.st_mode) == -1)
-    fatal ("Can't chmod (%s): errno %d\n", new_name, errno);
+  if (chmod (new_name, stat_buf.st_mode) != 0)
+    fatal ("Can't chmod (%s): %s", new_name, strerror (errno));
 }