From: Simon Marchi <simon.marchi@polymtl.ca>
To: gdb-patches@sourceware.org
Subject: Re: [PATCH] gdbsupport: fix path_join crash with -std=c++17 and -D_GLIBCXX_DEBUG
Date: Thu, 19 May 2022 08:08:54 -0400 [thread overview]
Message-ID: <95cfc364-3ec6-6ebb-bc28-26963a8198fd@polymtl.ca> (raw)
In-Reply-To: <20220504141840.1269433-1-simon.marchi@polymtl.ca>
On 2022-05-04 10:18, Simon Marchi wrote:
> When building GDB with -std=c++17 and -D_GLIBCXX_DEBUG=1, I get:
>
> $ ./gdb -nx --data-directory=data-directory -q -ex "maint selftest path_join"
> /usr/include/c++/11.2.0/string_view:233: constexpr const value_type& std::basic_string_view<_CharT, _Traits>::operator[](std::basic_string_view<_CharT, _Traits>::size_type) const [with _CharT = char; _Traits = std::char_traits<char>; std::basic_string_view<_CharT, _Traits>::const_reference = const char&; std::basic_string_view<_CharT, _Traits>::size_type = long unsigned int]: Assertion '__pos < this->_M_len' failed.
>
> The problem is that we're passing an empty string_view to
> IS_ABSOLUTE_PATH. IS_ABSOLUTE_PATH accesses [0] on that string_view,
> which is out-of-bounds.
>
> The reason this is not seen with -std less than c++17 is that our local
> copy of string_view (used with C++ < 17) does not have the assert in
> operator[], as that wouldn't work in a constexpr method:
>
> https://gitlab.com/gnutools/binutils-gdb/-/blob/5890af36e5112bcbb8d7555e63570f68466e6944/gdbsupport/gdb_string_view.h#L180
>
> IS_ABSOLUTE_PATH is normally used with null-terminated string. It's
> fine to pass an empty null-terminated string to IS_ABSOLUTE_PATH,
> because index 0 in such a string is valid. But not with an empty
> string_view.
>
> Fix that by avoiding the "call" to IS_ABSOLUTE_PATH if the string_view
> is empty.
>
> Change-Id: Idf4df961b63f513b3389235e93814c02b89ea32e
> ---
> gdbsupport/pathstuff.cc | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gdbsupport/pathstuff.cc b/gdbsupport/pathstuff.cc
> index 5b5a8eea9047..af10c6ebd2e8 100644
> --- a/gdbsupport/pathstuff.cc
> +++ b/gdbsupport/pathstuff.cc
> @@ -200,7 +200,7 @@ path_join (gdb::array_view<const gdb::string_view> paths)
> const gdb::string_view path = paths[i];
>
> if (i > 0)
> - gdb_assert (!IS_ABSOLUTE_PATH (path));
> + gdb_assert (path.empty () || !IS_ABSOLUTE_PATH (path));
>
> if (!ret.empty () && !IS_DIR_SEPARATOR (ret.back ()))
> ret += '/';
>
> base-commit: 5890af36e5112bcbb8d7555e63570f68466e6944
I pushed this.
Simon
prev parent reply other threads:[~2022-05-19 12:09 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-04 14:18 Simon Marchi
2022-05-19 12:08 ` Simon Marchi [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=95cfc364-3ec6-6ebb-bc28-26963a8198fd@polymtl.ca \
--to=simon.marchi@polymtl.ca \
--cc=gdb-patches@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).