From: Mark Wielaard <mark@klomp.org>
Date: Tue, 5 Jun 2018 20:27:25 +0000 (+0200)
Subject: libdw: Make sure dirarray is always properly freed in dwarf_getsrclines.
X-Git-Tag: elfutils-0.172~21
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=7009db70ca21d2b26cabd1c9fa1a50c35b6342b1;p=thirdparty%2Felfutils.git

libdw: Make sure dirarray is always properly freed in dwarf_getsrclines.

If there were more than 256 directories in the table and there was
illegal DWARF before we read them all, then we might not free the
dirarray (or the wrong one). Fix by defining the dirarray early
(before the first data sanity check) and making sure it is not
(still) equal to dirstack before freeing.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index b9f177dee..f0ce901de 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,9 @@
+2018-06-05  Mark Wielaard  <mark@klomp.org>
+
+	* dwarf_getsrclines.c (read_srclines): Define dirarray early and
+	check whether or not it is equal to dirstack on exit/out before
+	cleanup.
+
 2018-06-05  Mark Wielaard  <mark@klomp.org>
 
 	* dwarf_getalt.c (find_debug_altlink): id_path array should be 2
diff --git a/libdw/dwarf_getsrclines.c b/libdw/dwarf_getsrclines.c
index 790d4e49b..0c2efaa90 100644
--- a/libdw/dwarf_getsrclines.c
+++ b/libdw/dwarf_getsrclines.c
@@ -182,6 +182,17 @@ read_srclines (Dwarf *dbg,
       .discriminator = 0
     };
 
+  /* The dirs normally go on the stack, but if there are too many
+     we alloc them all.  Set up stack storage early, so we can check on
+     error if we need to free them or not.  */
+  struct dirlist
+  {
+    const char *dir;
+    size_t len;
+  };
+  struct dirlist dirstack[MAX_STACK_DIRS];
+  struct dirlist *dirarray = dirstack;
+
   if (unlikely (linep + 4 > lineendp))
     {
     invalid_data:
@@ -347,14 +358,6 @@ read_srclines (Dwarf *dbg,
 	goto invalid_data;
     }
 
-  struct dirlist
-  {
-    const char *dir;
-    size_t len;
-  };
-  struct dirlist dirstack[MAX_STACK_DIRS];
-  struct dirlist *dirarray = dirstack;
-
   /* Arrange the list in array form.  */
   ndirlist = ndirs;
   if (ndirlist >= MAX_STACK_DIRS)
@@ -1051,7 +1054,7 @@ read_srclines (Dwarf *dbg,
       free (state.linelist);
       state.linelist = ll;
     }
-  if (ndirlist >= MAX_STACK_DIRS)
+  if (dirarray != dirstack)
     free (dirarray);
   for (size_t i = MAX_STACK_FILES; i < nfilelist; i++)
     {