From: Tom Tromey <tromey@adacore.com>
To: gdb-patches@sourceware.org
Cc: Tom Tromey <tromey@adacore.com>
Subject: [PATCH] Avoid buffer overflow in ada_decode
Date: Wed, 16 Aug 2023 11:31:33 -0600 [thread overview]
Message-ID: <20230816173133.867606-1-tromey@adacore.com> (raw)
A bug report pointed out a buffer overflow in ada_decode, which Keith
helpfully analyzed. ada_decode had a logic error when the input was
all digits. While this isn't valid -- and would probably only appear
in fuzzer tests -- it still should be handled properly.
This patch adds a missing bounds check. Tested with the self-tests in
an asan build.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30639
---
gdb/ada-lang.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 1261ee8fa05..6e8d98bf4ea 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -57,6 +57,7 @@
#include "cli/cli-utils.h"
#include "gdbsupport/function-view.h"
#include "gdbsupport/byte-vector.h"
+#include "gdbsupport/selftest.h"
#include <algorithm>
#include "ada-exp.h"
#include "charset.h"
@@ -1377,7 +1378,7 @@ ada_decode (const char *encoded, bool wrap, bool operators)
i -= 1;
if (i > 1 && encoded[i] == '_' && encoded[i - 1] == '_')
len0 = i - 1;
- else if (encoded[i] == '$')
+ else if (i >= 0 && encoded[i] == '$')
len0 = i;
}
@@ -1574,6 +1575,18 @@ ada_decode (const char *encoded, bool wrap, bool operators)
return decoded;
}
+#ifdef GDB_SELF_TEST
+
+static void
+ada_decode_tests ()
+{
+ /* This isn't valid, but used to cause a crash. PR gdb/30639. The
+ result does not really matter very much. */
+ SELF_CHECK (ada_decode ("44") == "44");
+}
+
+#endif
+
/* Table for keeping permanent unique copies of decoded names. Once
allocated, names in this table are never released. While this is a
storage leak, it should not be significant unless there are massive
@@ -13977,4 +13990,8 @@ DWARF attribute."),
gdb::observers::new_objfile.attach (ada_new_objfile_observer, "ada-lang");
gdb::observers::free_objfile.attach (ada_free_objfile_observer, "ada-lang");
gdb::observers::inferior_exit.attach (ada_inferior_exit, "ada-lang");
+
+#ifdef GDB_SELF_TEST
+ selftests::register_test ("ada-decode", ada_decode_tests);
+#endif
}
--
2.40.1
next reply other threads:[~2023-08-16 17:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-16 17:31 Tom Tromey [this message]
2023-08-16 17:56 ` Keith Seitz
2023-08-16 19:07 ` Tom Tromey
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