file size check in _bfd_alloc_and_read

Message ID 20200219052623.GO5570@bubble.grove.modra.org
State New
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Series
  • file size check in _bfd_alloc_and_read
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Commit Message

Alan Modra Feb. 19, 2020, 5:26 a.m.
This replaces a few random file size checks with one that happens for
all _bfd_[m]alloc_and_read calls except constant size reads.

	* coffgen.c (_bfd_coff_get_external_symbols): Remove file size check.
	* elf.c (bfd_elf_get_str_section): Likewise.
	(_bfd_elf_slurp_version_tables): Likewise.
	* libbfd-in.h (_bfd_constant_p): Define.
	(_bfd_alloc_and_read, _bfd_malloc_and_read): Check read size against
	file size before allocating memory.
	* libbfd.h: Regenerate.


-- 
Alan Modra
Australia Development Lab, IBM

Patch

diff --git a/bfd/coffgen.c b/bfd/coffgen.c
index dda98394f1..daaaba95c5 100644
--- a/bfd/coffgen.c
+++ b/bfd/coffgen.c
@@ -1632,20 +1632,14 @@  _bfd_coff_get_external_symbols (bfd *abfd)
   size_t symesz;
   size_t size;
   void * syms;
-  ufile_ptr filesize;
 
   if (obj_coff_external_syms (abfd) != NULL)
     return TRUE;
 
-  /* Check for integer overflow and for unreasonable symbol counts.  */
-  filesize = bfd_get_file_size (abfd);
   symesz = bfd_coff_symesz (abfd);
-  if (_bfd_mul_overflow (obj_raw_syment_count (abfd), symesz, &size)
-      || (filesize != 0 && size > filesize))
+  if (_bfd_mul_overflow (obj_raw_syment_count (abfd), symesz, &size))
     {
       bfd_set_error (bfd_error_file_truncated);
-      _bfd_error_handler (_("%pB: corrupt symbol count: %#" PRIx64 ""),
-			  abfd, (uint64_t) obj_raw_syment_count (abfd));
       return FALSE;
     }
 
diff --git a/bfd/elf.c b/bfd/elf.c
index 7eb717b7ff..deb93b0a5a 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -296,7 +296,6 @@  bfd_elf_get_str_section (bfd *abfd, unsigned int shindex)
       /* Allocate and clear an extra byte at the end, to prevent crashes
 	 in case the string table is not terminated.  */
       if (shstrtabsize + 1 <= 1
-	  || shstrtabsize > bfd_get_file_size (abfd)
 	  || bfd_seek (abfd, offset, SEEK_SET) != 0
 	  || (shstrtab = _bfd_alloc_and_read (abfd, shstrtabsize + 1,
 					      shstrtabsize)) == NULL)
@@ -8586,19 +8585,6 @@  error_return_verref:
 	  goto error_return;
 	}
 
-      ufile_ptr filesize = bfd_get_file_size (abfd);
-      if (filesize > 0 && filesize < hdr->sh_size)
-	{
-	  /* PR 24708: Avoid attempts to allocate a ridiculous amount
-	     of memory.  */
-	  bfd_set_error (bfd_error_no_memory);
-	  _bfd_error_handler
-	    /* xgettext:c-format */
-	    (_("error: %pB version reference section is too large (%#" PRIx64 " bytes)"),
-	     abfd, (uint64_t) hdr->sh_size);
-	  goto error_return_verref;
-	}
-
       if (bfd_seek (abfd, hdr->sh_offset, SEEK_SET) != 0)
 	goto error_return_verref;
       contents = _bfd_malloc_and_read (abfd, hdr->sh_size, hdr->sh_size);
diff --git a/bfd/libbfd-in.h b/bfd/libbfd-in.h
index a8f9bcd47d..6d796b7ef8 100644
--- a/bfd/libbfd-in.h
+++ b/bfd/libbfd-in.h
@@ -904,10 +904,26 @@  extern bfd_vma _bfd_safe_read_leb128
   ((*res) = (a), (*res) *= (b), (b) != 0 && (*res) / (b) != (a))
 #endif
 
+#ifdef __GNUC__
+#define _bfd_constant_p(v) __builtin_constant_p (v)
+#else
+#define _bfd_constant_p(v) 0
+#endif
+
 static inline bfd_byte *
 _bfd_alloc_and_read (bfd *abfd, bfd_size_type asize, bfd_size_type rsize)
 {
-  bfd_byte *mem = bfd_alloc (abfd, asize);
+  bfd_byte *mem;
+  if (!_bfd_constant_p (rsize))
+    {
+      ufile_ptr filesize = bfd_get_file_size (abfd);
+      if (filesize != 0 && rsize > filesize)
+	{
+	  bfd_set_error (bfd_error_file_truncated);
+	  return NULL;
+	}
+    }
+  mem = bfd_alloc (abfd, asize);
   if (mem != NULL)
     {
       if (bfd_bread (mem, rsize, abfd) == rsize)
@@ -920,7 +936,17 @@  _bfd_alloc_and_read (bfd *abfd, bfd_size_type asize, bfd_size_type rsize)
 static inline bfd_byte *
 _bfd_malloc_and_read (bfd *abfd, bfd_size_type asize, bfd_size_type rsize)
 {
-  bfd_byte *mem = bfd_malloc (asize);
+  bfd_byte *mem;
+  if (!_bfd_constant_p (rsize))
+    {
+      ufile_ptr filesize = bfd_get_file_size (abfd);
+      if (filesize != 0 && rsize > filesize)
+	{
+	  bfd_set_error (bfd_error_file_truncated);
+	  return NULL;
+	}
+    }
+  mem = bfd_malloc (asize);
   if (mem != NULL)
     {
       if (bfd_bread (mem, rsize, abfd) == rsize)