[binutils-gdb] Fix infinite loop in is_linked_with_cygwin_dll

[binutils-gdb] Fix infinite loop in is_linked_with_cygwin_dll

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=29514b87281c438543e4fc6ddda245dc194d5677

commit 29514b87281c438543e4fc6ddda245dc194d5677
Author: Tom Tromey <tromey@adacore.com>
Date:   Thu Apr 23 12:15:28 2020 -0600

    Fix infinite loop in is_linked_with_cygwin_dll
    
    There were some Windows timeouts after the last merge.  Debugging
    showed that these were caused by an infinite loop in
    is_linked_with_cygwin_dll when reading C:\Windows\SysWOW64\win32u.dll.
    
    This patch fixes the problem by ensuring that the loop always makes
    progress.
    
    gdb/ChangeLog
    2020-04-23  Tom Tromey  <tromey@adacore.com>
    
            * windows-tdep.c (is_linked_with_cygwin_dll): Always update "iter"
            in loop.

Diff:
---
 gdb/ChangeLog      |  5 +++++
 gdb/windows-tdep.c | 17 +++++++++--------
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 145328dda1c..85fa7cf5f76 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-23  Tom Tromey  <tromey@adacore.com>
+
+	* windows-tdep.c (is_linked_with_cygwin_dll): Always update "iter"
+	in loop.
+
 2020-04-23  Luis Machado  <luis.machado@linaro.org>
 
 	* dwarf2/frame-tailcall.c (dwarf2_tailcall_sniffer_first): Use
diff --git a/gdb/windows-tdep.c b/gdb/windows-tdep.c
index e2b7960829f..153ad132b96 100644
--- a/gdb/windows-tdep.c
+++ b/gdb/windows-tdep.c
@@ -1071,18 +1071,19 @@ range [0x%" BFD_VMA_FMT "x, 0x%" BFD_VMA_FMT "x[."),
 
       const gdb_byte *name = &idata_contents[name_va - idata_section_va];
 
-      /* Make sure we don't overshoot the end of the section with the streq.  */
-      if (name + sizeof (CYGWIN_DLL_NAME) > end)
-	continue;
-
-      /* Finally, check if this is the dll name we are looking for.  */
-      if (streq ((const char *) name, CYGWIN_DLL_NAME))
-	return true;
+      /* Make sure we don't overshoot the end of the section with the
+	 streq.  */
+      if (name + sizeof (CYGWIN_DLL_NAME) <= end)
+	{
+	  /* Finally, check if this is the dll name we are looking for.  */
+	  if (streq ((const char *) name, CYGWIN_DLL_NAME))
+	    return true;
+	}
 
       iter += sizeof (pe_import_directory_entry);
     }
 
-    return false;
+  return false;
 }
 
 void _initialize_windows_tdep ();