Bug 107741

Summary:	DBUS_MALLOC attribute on dbus_realloc() is inappropriate
Product:	dbus	Reporter:	Simon McVittie <smcv>
Component:	core	Assignee:	Simon McVittie <smcv>
Status:	RESOLVED FIXED	QA Contact:	D-Bus Maintainers <dbus>
Severity:	normal
Priority:	medium	Keywords:	patch
Version:	git master
Hardware:	Other
OS:	All
Whiteboard:	review+
i915 platform:		i915 features:
Attachments:	Do not apply __attribute__((__malloc__)) to dbus_realloc()

Description Simon McVittie 2018-08-29 18:45:44 UTC

Created attachment 141362 [details] [review]
Do not apply __attribute__((__malloc__)) to dbus_realloc()

As noted in GLib commit c879f50f, gcc's interpretation of the malloc
attribute has become more strict over time, which could result in
miscompilation. The new definition is that in addition to assuming
that the returned memory block is newly-allocated, gcc now assumes
that it does not contain any valid pointers. This is OK for
uninitialized or zero-initialized memory returned by dbus_malloc()
or dbus_malloc0(), but not valid for dbus_realloc(), which might be
used for a dynamically-sized array of (structures containing)
valid pointers.

See https://gitlab.gnome.org/GNOME/glib/issues/1465

---

Also proposed for dbus-1.12 and dbus-1.10, since silent miscompilation is scary and the patch is trivial.

The annotation was added by Bug #32710.

Comment 1 Philip Withnall 2018-08-30 09:42:36 UTC

Comment on attachment 141362 [details] [review]
Do not apply __attribute__((__malloc__)) to dbus_realloc()

Review of attachment 141362 [details] [review]:
-----------------------------------------------------------------

r+++++

Comment 2 Simon McVittie 2018-08-30 16:48:37 UTC

Thanks, will merge when CI completes (should be in dbus 1.13.8, 1.12.12 and 1.10.28).

Comment 3 Simon McVittie 2018-08-30 17:34:15 UTC

Fixed in git for 1.13.8, 1.12.12 and 1.10.28

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