libdw: Check there are any header bytes in rnglists

We tried to read the rnglists header length and only then checked if
there were any bytes left. Make sure to check there are at least 4
bytes for the initial unit length.

	* libdw/libdwP.h (__libdw_cu_ranges_base): Check before initial
	unit_length read.

https://sourceware.org/bugzilla/show_bug.cgi?id=34385

Reported-by: Karan Kurani <karankurani3k@gmail.com>
Signed-off-by: Mark Wielaard <mark@klomp.org>

diff --git a/libdw/libdwP.h b/libdw/libdwP.h
index 5e1029bd2ac2444399ada817cc9dd20c2c4ffb5d..25391396ff6b17711dc8be49cb53df0a1b6682d1 100644 (file)
--- a/libdw/libdwP.h
+++ b/libdw/libdwP.h
@@ -1373,6 +1373,8 @@ __libdw_cu_ranges_base (Dwarf_CU *cu)
              const unsigned char *const dataend
                = (unsigned char *) data->d_buf + data->d_size;
 
+             if (unlikely (readp > dataend - 4))
+               goto no_header;
              uint64_t unit_length = read_4ubyte_unaligned_inc (dbg, readp);
              unsigned int offset_size = 4;
              if (unlikely (unit_length == 0xffffffff))