1 files changed, 35 insertions, 12 deletions

diff --git a/libbacktrace/dwarf.c b/libbacktrace/dwarf.c
index 68ebb4e3a..4e13fc541 100644
--- a/libbacktrace/dwarf.c
+++ b/libbacktrace/dwarf.c
@@ -44,8 +44,22 @@ POSSIBILITY OF SUCH DAMAGE.  */
 #include "internal.h"
 
 #if !defined(HAVE_DECL_STRNLEN) || !HAVE_DECL_STRNLEN
-/* The function is defined in libiberty if needed.  */
-extern size_t strnlen (const char *, size_t);
+
+/* If strnlen is not declared, provide our own version.  */
+
+static size_t
+xstrnlen (const char *s, size_t maxlen)
+{
+  size_t i;
+
+  for (i = 0; i < maxlen; ++i)
+    if (s[i] == '\0')
+      break;
+  return i;
+}
+
+#define strnlen xstrnlen
+
 #endif
 
 /* A buffer to read DWARF info.  */
@@ -524,10 +538,12 @@ read_uleb128 (struct dwarf_buf *buf)
 {
   uint64_t ret;
   unsigned int shift;
+  int overflow;
   unsigned char b;
 
   ret = 0;
   shift = 0;
+  overflow = 0;
   do
     {
       const unsigned char *p;
@@ -536,14 +552,17 @@ read_uleb128 (struct dwarf_buf *buf)
       if (!advance (buf, 1))
 	return 0;
       b = *p;
-      ret |= ((uint64_t) (b & 0x7f)) << shift;
+      if (shift < 64)
+	ret |= ((uint64_t) (b & 0x7f)) << shift;
+      else if (!overflow)
+	{
+	  dwarf_buf_error (buf, "LEB128 overflows uint64_t");
+	  overflow = 1;
+	}
       shift += 7;
     }
   while ((b & 0x80) != 0);
 
-  if (shift > 64)
-    dwarf_buf_error (buf, "LEB128 overflows uint64_5");
-
   return ret;
 }
 
@@ -554,10 +573,12 @@ read_sleb128 (struct dwarf_buf *buf)
 {
   uint64_t val;
   unsigned int shift;
+  int overflow;
   unsigned char b;
 
   val = 0;
   shift = 0;
+  overflow = 0;
   do
     {
       const unsigned char *p;
@@ -566,15 +587,18 @@ read_sleb128 (struct dwarf_buf *buf)
       if (!advance (buf, 1))
 	return 0;
       b = *p;
-      val |= ((uint64_t) (b & 0x7f)) << shift;
+      if (shift < 64)
+	val |= ((uint64_t) (b & 0x7f)) << shift;
+      else if (!overflow)
+	{
+	  dwarf_buf_error (buf, "signed LEB128 overflows uint64_t");
+	  overflow = 1;
+	}
       shift += 7;
     }
   while ((b & 0x80) != 0);
 
-  if (shift > 64)
-    dwarf_buf_error (buf, "signed LEB128 overflows uint64_t");
-
-  if ((b & 0x40) != 0)
+  if ((b & 0x40) != 0 && shift < 64)
     val |= ((uint64_t) -1) << shift;
 
   return (int64_t) val;
@@ -1262,7 +1286,6 @@ build_address_map (struct backtrace_state *state,
 	}
 
       unit_buf = info;
-      unit_buf.start = info.buf;
       unit_buf.left = len;
 
       if (!advance (&info, len))