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74df22453c
The __alloc_size annotation for kmemdup() was getting disabled under
KUnit testing because the replaced fortify_panic macro implementation
was using "return NULL" as a way to survive the sanity checking. But
having the chance to return NULL invalidated __alloc_size, so kmemdup
was not passing the __builtin_dynamic_object_size() tests any more:
[23:26:18] [PASSED] fortify_test_alloc_size_kmalloc_const
[23:26:19] # fortify_test_alloc_size_kmalloc_dynamic: EXPECTATION FAILED at lib/fortify_kunit.c:265
[23:26:19] Expected __builtin_dynamic_object_size(p, 1) == expected, but
[23:26:19] __builtin_dynamic_object_size(p, 1) == -1 (0xffffffffffffffff)
[23:26:19] expected == 11 (0xb)
[23:26:19] __alloc_size() not working with __bdos on kmemdup("hello there", len, gfp)
[23:26:19] [FAILED] fortify_test_alloc_size_kmalloc_dynamic
Normal builds were not affected: __alloc_size continued to work there.
Use a zero-sized allocation instead, which allows __alloc_size to
behave.
Fixes: 4ce615e798 ("fortify: Provide KUnit counters for failure testing")
Fixes: fa4a3f86d4 ("fortify: Add KUnit tests for runtime overflows")
Link: https://lore.kernel.org/r/20240501232937.work.532-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.