From 2db20b97f1dc3e5dce3d6ed74a8a62f0dede8c80 Mon Sep 17 00:00:00 2001
From: Alan Modra <amodra@gmail.com>
Date: Wed, 9 Aug 2023 09:58:36 +0930
Subject: [PATCH] gdb: warn unused result for bfd IO functions

This fixes the compilation warnings introduced by my bfdio.c patch.

The removed bfd_seeks in coff_symfile_read date back to 1994, commit
7f4c859520, prior to which the file used stdio rather than bfd to read
symbols.  Since it now uses bfd to read the file there should be no
need to synchronise to bfd's idea of the file position.  I also fixed
a potential uninitialised memory access.

Approved-By: Andrew Burgess <aburgess@redhat.com>

Upstream-Status: Backport from [https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=2db20b97f1dc3e5dce3d6ed74a8a62f0dede8c80]
CVE: CVE-2023-39130
Signed-off-by: Deepthi Hemraj <Deepthi.Hemraj@windriver.com>
---
 gdb/coff-pe-read.c | 114 +++++++++++++++++++++++++++++----------------
 gdb/coffread.c     |  27 ++---------
 gdb/dbxread.c      |   7 +--
 gdb/xcoffread.c    |   5 +-
 4 files changed, 85 insertions(+), 68 deletions(-)

diff --git a/gdb/coff-pe-read.c b/gdb/coff-pe-read.c
--- a/gdb/coff-pe-read.c
+++ b/gdb/coff-pe-read.c
@@ -291,23 +291,31 @@ read_pe_truncate_name (char *dll_name)
 
 /* Low-level support functions, direct from the ld module pe-dll.c.  */
 static unsigned int
-pe_get16 (bfd *abfd, int where)
+pe_get16 (bfd *abfd, int where, bool *fail)
 {
   unsigned char b[2];
 
-  bfd_seek (abfd, (file_ptr) where, SEEK_SET);
-  bfd_bread (b, (bfd_size_type) 2, abfd);
+  if (bfd_seek (abfd, where, SEEK_SET) != 0
+      || bfd_bread (b, 2, abfd) != 2)
+    {
+      *fail = true;
+      return 0;
+    }
   return b[0] + (b[1] << 8);
 }
 
 static unsigned int
-pe_get32 (bfd *abfd, int where)
+pe_get32 (bfd *abfd, int where, bool *fail)
 {
   unsigned char b[4];
 
-  bfd_seek (abfd, (file_ptr) where, SEEK_SET);
-  bfd_bread (b, (bfd_size_type) 4, abfd);
-  return b[0] + (b[1] << 8) + (b[2] << 16) + (b[3] << 24);
+  if (bfd_seek (abfd, where, SEEK_SET) != 0
+      || bfd_bread (b, 4, abfd) != 4)
+    {
+      *fail = true;
+      return 0;
+    }
+  return b[0] + (b[1] << 8) + (b[2] << 16) + ((unsigned) b[3] << 24);
 }
 
 static unsigned int
@@ -323,7 +331,7 @@ pe_as32 (void *ptr)
 {
   unsigned char *b = (unsigned char *) ptr;
 
-  return b[0] + (b[1] << 8) + (b[2] << 16) + (b[3] << 24);
+  return b[0] + (b[1] << 8) + (b[2] << 16) + ((unsigned) b[3] << 24);
 }
 
 /* Read the (non-debug) export symbol table from a portable
@@ -376,37 +384,50 @@ read_pe_exported_syms (minimal_symbol_re
 	     || strcmp (target, "pei-i386") == 0
 	     || strcmp (target, "pe-arm-wince-little") == 0
 	     || strcmp (target, "pei-arm-wince-little") == 0);
+
+  /* Possibly print a debug message about DLL not having a valid format.  */
+  auto maybe_print_debug_msg = [&] () -> void {
+    if (debug_coff_pe_read)
+      fprintf_unfiltered (gdb_stdlog, _("%s doesn't appear to be a DLL\n"),
+					bfd_get_filename (dll));
+  };
+
   if (!is_pe32 && !is_pe64)
-    {
-      /* This is not a recognized PE format file.  Abort now, because
-	 the code is untested on anything else.  *FIXME* test on
-	 further architectures and loosen or remove this test.  */
-      return;
-    }
+    return maybe_print_debug_msg ();
 
   /* Get pe_header, optional header and numbers of export entries.  */
-  pe_header_offset = pe_get32 (dll, 0x3c);
+  bool fail = false;
+  pe_header_offset = pe_get32 (dll, 0x3c, &fail);
+  if (fail)
+    return maybe_print_debug_msg ();
   opthdr_ofs = pe_header_offset + 4 + 20;
   if (is_pe64)
-    num_entries = pe_get32 (dll, opthdr_ofs + 108);
+    num_entries = pe_get32 (dll, opthdr_ofs + 108, &fail);
   else
-    num_entries = pe_get32 (dll, opthdr_ofs + 92);
+    num_entries = pe_get32 (dll, opthdr_ofs + 92, &fail);
+  if (fail)
+    return maybe_print_debug_msg ();
 
   if (num_entries < 1)		/* No exports.  */
     return;
   if (is_pe64)
     {
-      export_opthdrrva = pe_get32 (dll, opthdr_ofs + 112);
-      export_opthdrsize = pe_get32 (dll, opthdr_ofs + 116);
+      export_opthdrrva = pe_get32 (dll, opthdr_ofs + 112, &fail);
+      export_opthdrsize = pe_get32 (dll, opthdr_ofs + 116, &fail);
     }
   else
     {
-      export_opthdrrva = pe_get32 (dll, opthdr_ofs + 96);
-      export_opthdrsize = pe_get32 (dll, opthdr_ofs + 100);
+      export_opthdrrva = pe_get32 (dll, opthdr_ofs + 96, &fail);
+      export_opthdrsize = pe_get32 (dll, opthdr_ofs + 100, &fail);
     }
-  nsections = pe_get16 (dll, pe_header_offset + 4 + 2);
+  if (fail)
+    return maybe_print_debug_msg ();
+
+  nsections = pe_get16 (dll, pe_header_offset + 4 + 2, &fail);
   secptr = (pe_header_offset + 4 + 20 +
-	    pe_get16 (dll, pe_header_offset + 4 + 16));
+	    pe_get16 (dll, pe_header_offset + 4 + 16, &fail));
+  if (fail)
+    return maybe_print_debug_msg ();
   expptr = 0;
   export_size = 0;
 
@@ -415,12 +436,13 @@ read_pe_exported_syms (minimal_symbol_re
     {
       char sname[8];
       unsigned long secptr1 = secptr + 40 * i;
-      unsigned long vaddr = pe_get32 (dll, secptr1 + 12);
-      unsigned long vsize = pe_get32 (dll, secptr1 + 16);
-      unsigned long fptr = pe_get32 (dll, secptr1 + 20);
-
-      bfd_seek (dll, (file_ptr) secptr1, SEEK_SET);
-      bfd_bread (sname, (bfd_size_type) sizeof (sname), dll);
+      unsigned long vaddr = pe_get32 (dll, secptr1 + 12, &fail);
+      unsigned long vsize = pe_get32 (dll, secptr1 + 16, &fail);
+      unsigned long fptr = pe_get32 (dll, secptr1 + 20, &fail);
+
+      if (fail
+	  || bfd_seek (dll, secptr1, SEEK_SET) != 0
+	  || bfd_bread (sname, sizeof (sname), dll) != sizeof (sname))
 
       if ((strcmp (sname, ".edata") == 0)
 	  || (vaddr <= export_opthdrrva && export_opthdrrva < vaddr + vsize))
@@ -461,16 +483,18 @@ read_pe_exported_syms (minimal_symbol_re
   for (i = 0; i < nsections; i++)
     {
       unsigned long secptr1 = secptr + 40 * i;
-      unsigned long vsize = pe_get32 (dll, secptr1 + 8);
-      unsigned long vaddr = pe_get32 (dll, secptr1 + 12);
-      unsigned long characteristics = pe_get32 (dll, secptr1 + 36);
+      unsigned long vsize = pe_get32 (dll, secptr1 + 8, &fail);
+      unsigned long vaddr = pe_get32 (dll, secptr1 + 12, &fail);
+      unsigned long characteristics = pe_get32 (dll, secptr1 + 36, &fail);
       char sec_name[SCNNMLEN + 1];
       int sectix;
       unsigned int bfd_section_index;
       asection *section;
 
-      bfd_seek (dll, (file_ptr) secptr1 + 0, SEEK_SET);
-      bfd_bread (sec_name, (bfd_size_type) SCNNMLEN, dll);
+      if (fail
+	  || bfd_seek (dll, secptr1 + 0, SEEK_SET) != 0
+	  || bfd_bread (sec_name, SCNNMLEN, dll) != SCNNMLEN)
+	return maybe_print_debug_msg ();
       sec_name[SCNNMLEN] = '\0';
 
       sectix = read_pe_section_index (sec_name);
@@ -509,8 +533,9 @@ read_pe_exported_syms (minimal_symbol_re
   gdb::def_vector<unsigned char> expdata_storage (export_size);
   expdata = expdata_storage.data ();
 
-  bfd_seek (dll, (file_ptr) expptr, SEEK_SET);
-  bfd_bread (expdata, (bfd_size_type) export_size, dll);
+  if (bfd_seek (dll, expptr, SEEK_SET) != 0
+      || bfd_bread (expdata, export_size, dll) != export_size)
+    return maybe_print_debug_msg ();
   erva = expdata - export_rva;
 
   nexp = pe_as32 (expdata + 24);
@@ -658,20 +683,27 @@ pe_text_section_offset (struct bfd *abfd
     }
 
   /* Get pe_header, optional header and numbers of sections.  */
-  pe_header_offset = pe_get32 (abfd, 0x3c);
-  nsections = pe_get16 (abfd, pe_header_offset + 4 + 2);
+  bool fail = false;
+  pe_header_offset = pe_get32 (abfd, 0x3c, &fail);
+  if (fail)
+    return DEFAULT_COFF_PE_TEXT_SECTION_OFFSET;
+  nsections = pe_get16 (abfd, pe_header_offset + 4 + 2, &fail);
   secptr = (pe_header_offset + 4 + 20 +
-	    pe_get16 (abfd, pe_header_offset + 4 + 16));
+	    pe_get16 (abfd, pe_header_offset + 4 + 16, &fail));
+  if (fail)
+    return DEFAULT_COFF_PE_TEXT_SECTION_OFFSET;
 
   /* Get the rva and size of the export section.  */
   for (i = 0; i < nsections; i++)
     {
       char sname[SCNNMLEN + 1];
       unsigned long secptr1 = secptr + 40 * i;
-      unsigned long vaddr = pe_get32 (abfd, secptr1 + 12);
+      unsigned long vaddr = pe_get32 (abfd, secptr1 + 12, &fail);
 
-      bfd_seek (abfd, (file_ptr) secptr1, SEEK_SET);
-      bfd_bread (sname, (bfd_size_type) SCNNMLEN, abfd);
+      if (fail
+	  || bfd_seek (abfd, secptr1, SEEK_SET) != 0
+	  || bfd_bread (sname, SCNNMLEN, abfd) != SCNNMLEN)
+	return DEFAULT_COFF_PE_TEXT_SECTION_OFFSET;
       sname[SCNNMLEN] = '\0';
       if (strcmp (sname, ".text") == 0)
 	return vaddr;
diff --git a/gdb/coffread.c b/gdb/coffread.c
--- a/gdb/coffread.c
+++ b/gdb/coffread.c
@@ -690,8 +690,6 @@ coff_symfile_read (struct objfile *objfi
 
       /* FIXME: dubious.  Why can't we use something normal like
 	 bfd_get_section_contents?  */
-      bfd_seek (abfd, abfd->where, 0);
-
       stabstrsize = bfd_section_size (info->stabstrsect);
 
       coffstab_build_psymtabs (objfile,
@@ -780,22 +778,6 @@ coff_symtab_read (minimal_symbol_reader
 
   scoped_free_pendings free_pending;
 
-  /* Work around a stdio bug in SunOS4.1.1 (this makes me nervous....
-     it's hard to know I've really worked around it.  The fix should
-     be harmless, anyway).  The symptom of the bug is that the first
-     fread (in read_one_sym), will (in my example) actually get data
-     from file offset 268, when the fseek was to 264 (and ftell shows
-     264).  This causes all hell to break loose.  I was unable to
-     reproduce this on a short test program which operated on the same
-     file, performing (I think) the same sequence of operations.
-
-     It stopped happening when I put in this (former) rewind().
-
-     FIXME: Find out if this has been reported to Sun, whether it has
-     been fixed in a later release, etc.  */
-
-  bfd_seek (objfile->obfd, 0, 0);
-
   /* Position to read the symbol table.  */
   val = bfd_seek (objfile->obfd, symtab_offset, 0);
   if (val < 0)
@@ -1285,12 +1267,13 @@ init_stringtab (bfd *abfd, file_ptr offs
   if (bfd_seek (abfd, offset, 0) < 0)
     return -1;
 
-  val = bfd_bread ((char *) lengthbuf, sizeof lengthbuf, abfd);
-  length = bfd_h_get_32 (symfile_bfd, lengthbuf);
-
+  val = bfd_bread (lengthbuf, sizeof lengthbuf, abfd);
   /* If no string table is needed, then the file may end immediately
      after the symbols.  Just return with `stringtab' set to null.  */
-  if (val != sizeof lengthbuf || length < sizeof lengthbuf)
+  if (val != sizeof lengthbuf)
+    return 0;
+  length = bfd_h_get_32 (symfile_bfd, lengthbuf);
+  if (length < sizeof lengthbuf)
     return 0;
 
   storage->reset ((char *) xmalloc (length));
diff --git a/gdb/dbxread.c b/gdb/dbxread.c
--- a/gdb/dbxread.c
+++ b/gdb/dbxread.c
@@ -812,7 +812,8 @@ stabs_seek (int sym_offset)
       symbuf_left -= sym_offset;
     }
   else
-    bfd_seek (symfile_bfd, sym_offset, SEEK_CUR);
+    if (bfd_seek (symfile_bfd, sym_offset, SEEK_CUR) != 0)
+      perror_with_name (bfd_get_filename (symfile_bfd));
 }
 
 #define INTERNALIZE_SYMBOL(intern, extern, abfd)			\
@@ -2095,8 +2096,8 @@ dbx_expand_psymtab (legacy_psymtab *pst,
       symbol_size = SYMBOL_SIZE (pst);
 
       /* Read in this file's symbols.  */
-      bfd_seek (objfile->obfd, SYMBOL_OFFSET (pst), SEEK_SET);
-      read_ofile_symtab (objfile, pst);
+      if (bfd_seek (objfile->obfd, SYMBOL_OFFSET (pst), SEEK_SET) == 0)
+	read_ofile_symtab (objfile, pst);
     }
 
   pst->readin = true;
diff --git a/gdb/xcoffread.c b/gdb/xcoffread.c
--- a/gdb/xcoffread.c
+++ b/gdb/xcoffread.c
@@ -865,8 +865,9 @@ enter_line_range (struct subfile *subfil
 
   while (curoffset <= limit_offset)
     {
-      bfd_seek (abfd, curoffset, SEEK_SET);
-      bfd_bread (ext_lnno, linesz, abfd);
+      if (bfd_seek (abfd, curoffset, SEEK_SET) != 0
+	  || bfd_bread (ext_lnno, linesz, abfd) != linesz)
+	return;
       bfd_coff_swap_lineno_in (abfd, ext_lnno, &int_lnno);
 
       /* Find the address this line represents.  */
-- 
2.39.3
