From 033bc52bb6190393c8eed80925fa78cc35b40c6d Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Wed, 16 Aug 2023 11:29:19 -0600 Subject: [PATCH] Avoid buffer overflow in ada_decode 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 Reviewed-by: Keith Seitz --- 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 4a9a6e0f38f..2f934b1e79a 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 #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 @@ Suppress: 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 @@ -13984,4 +13997,8 @@ 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 } -- 2.30.2