1a83a716ec
As long as krealloc() is called with __GFP_ZERO consistently, starting with the initial memory allocation, __GFP_ZERO should be fully honored. However, if for an existing allocation krealloc() is called with a decreased size, it is not ensured that the spare portion the allocation is zeroed. Thus, if krealloc() is subsequently called with a larger size again, __GFP_ZERO can't be fully honored, since we don't know the previous size, but only the bucket size. Example: buf = kzalloc(64, GFP_KERNEL); memset(buf, 0xff, 64); buf = krealloc(buf, 48, GFP_KERNEL | __GFP_ZERO); /* After this call the last 16 bytes are still 0xff. */ buf = krealloc(buf, 64, GFP_KERNEL | __GFP_ZERO); Fix this, by explicitly setting spare memory to zero, when shrinking an allocation with __GFP_ZERO flag set or init_on_alloc enabled. Link: https://lkml.kernel.org/r/20240812223707.32049-1-dakr@kernel.org Signed-off-by: Danilo Krummrich <dakr@kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: David Rientjes <rientjes@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.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.