c9e48947e1
This affects the new `g_string_replace()` code which landed on `main` a few days ago. It does not affect the old implementation of `g_string_replace()`. The code for the `f_len == 0` (needle is an empty string) case was modifying `string` in the loop, without updating any of the string pointers into it. If the replacement was long enough (or inserted enough times), this would trigger a realloc of `string->str` and cause all the string pointers to be dangling. Fix this by pulling the `f_len == 0` code out into a separate branch and loop, rather than trying to integrate it into the main loop. This simplifies the main loop significantly, and makes both easier to verify. An alternative approach, which doesn’t involve splitting the `f_len == 0` case out, might have been to track the positions using indexes rather than string pointers. I think the approach in this commit is better, though, as it removes the possibility of `f_len == 0` entirely from the loop, which makes it much easier to verify termination of the loop. Add more tests to validate this, including the test from oss-fuzz which triggered the realloc and found the heap buffer overflow. The new tests have also been run against the _old_ implementation of `g_string_replace()` to ensure its behaviour (particularly around `f_len == 0 && limit > 0`) has not changed. Signed-off-by: Philip Withnall <pwithnall@gnome.org> oss-fuzz#371043019
GLib
GLib is the low-level core library that forms the basis for projects such as GTK and GNOME. It provides data structure handling for C, portability wrappers, and interfaces for such runtime functionality as an event loop, threads, dynamic loading, and an object system.
The official download locations are: https://download.gnome.org/sources/glib
The official web site is: https://www.gtk.org/
Installation
See the file ‘INSTALL.md’. There is separate and more in-depth documentation for building GLib on Windows.
Supported versions
Upstream GLib only supports the most recent stable release series, the previous stable release series, and the current development release series. All older versions are not supported upstream and may contain bugs, some of which may be exploitable security vulnerabilities.
See SECURITY.md for more details.
Documentation
API documentation is available online for GLib for the:
Discussion
If you have a question about how to use GLib, seek help on GNOME’s Discourse
instance. Alternatively, ask a question
on StackOverflow and tag it glib.
Reporting bugs
Bugs should be reported to the GNOME issue tracking system. You will need to create an account for yourself. You may also submit bugs by e-mail (without an account) by e-mailing incoming+gnome-glib-658-issue-@gitlab.gnome.org, but this will give you a degraded experience.
Bugs are for reporting problems in GLib itself, not for asking questions about how to use it. To ask questions, use one of our discussion forums.
In bug reports please include:
- Information about your system. For instance:
- What operating system and version
- For Linux, what version of the C library
- And anything else you think is relevant.
- How to reproduce the bug.
- If you can reproduce it with one of the test programs that are built
in the
tests/subdirectory, that will be most convenient. Otherwise, please include a short test program that exhibits the behavior. As a last resort, you can also provide a pointer to a larger piece of software that can be downloaded.
- If you can reproduce it with one of the test programs that are built
in the
- If the bug was a crash, the exact text that was printed out when the crash occurred.
- Further information such as stack traces may be useful, but is not necessary.
Contributing to GLib
Please follow the contribution guide to know how to start contributing to GLib.
Patches should be submitted as merge requests to gitlab.gnome.org. Note that you will need to be logged in to the site to use this page. If the patch fixes an existing issue, please refer to the issue in your commit message with the following notation (for issue 123):
Closes: #123
Otherwise, create a new merge request that introduces the change. Filing a separate issue is not required.