From: Simon Marchi <simon.marchi@polymtl.ca>
Date: Fri, 23 Jul 2021 04:32:23 +0000 (-0400)
Subject: gdb: fix nr_bits gdb_assert in append_flags_type_field
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=602885d8087f6ab35c8b9fd8ff0d5240a0b040a0;p=binutils-gdb.git

gdb: fix nr_bits gdb_assert in append_flags_type_field

The assertion

    gdb_assert (nr_bits >= 1 && nr_bits <= type_bitsize);

is not correct.  Well, it's correct in that we do want the number of
bits to be in the range [1, type_bitsize].  But we don't check anywhere
that the end of the specified flag is within the containing type.

The following code should generate a failed assertion, as the flag goes
past the 32 bits of the underlying type, but it's currently not caught:

    static void
    test_print_flag (gdbarch *arch)
    {
      type *flags_type = arch_flags_type (arch, "test_type", 32);
      type *field_type = builtin_type (arch)->builtin_uint32;
      append_flags_type_field (flags_type, 31, 2, field_type, "invalid");
    }

(You can test this by registering it as a selftest using
selftests::register_test_foreach_arc and running.)

Change the assertion to verify that the end bit is within the range of
the underlying type.  This implicitly verifies that nr_bits is not
too big as well, so we don't need a separate assertion for that.

Change-Id: I9be79e5fd7a5917bf25b03b598727e6274c892e8
Co-Authored-By: Tony Tye <Tony.Tye@amd.com>
---

diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index f76cafda8b4..5ba0e8d0eb9 100644
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -5839,7 +5839,7 @@ append_flags_type_field (struct type *type, int start_bitpos, int nr_bits,
   gdb_assert (type->code () == TYPE_CODE_FLAGS);
   gdb_assert (type->num_fields () + 1 <= type_bitsize);
   gdb_assert (start_bitpos >= 0 && start_bitpos < type_bitsize);
-  gdb_assert (nr_bits >= 1 && nr_bits <= type_bitsize);
+  gdb_assert (nr_bits >= 1 && (start_bitpos + nr_bits) <= type_bitsize);
   gdb_assert (name != NULL);
 
   TYPE_FIELD_NAME (type, field_nr) = xstrdup (name);