598a0717a8
Patch series "mm/slab: Improved sanity checking". This adds defenses against slab cache confusion (as seen in real-world exploits[1]) and gracefully handles type confusions when trying to look up slab caches from an arbitrary page. (Also is patch 3: new LKDTM tests for these defenses as well as for the existing double-free detection. This patch (of 3): When building under CONFIG_SLAB_FREELIST_HARDENING, it makes sense to perform sanity-checking on the assumed slab cache during kmem_cache_free() to make sure the kernel doesn't mix freelists across slab caches and corrupt memory (as seen in the exploitation of flaws like CVE-2018-9568[1]). Note that the prior code might WARN() but still corrupt memory (i.e. return the assumed cache instead of the owned cache). There is no noticeable performance impact (changes are within noise). Measuring parallel kernel builds, I saw the following with CONFIG_SLAB_FREELIST_HARDENED, before and after this patch: before: Run times: 288.85 286.53 287.09 287.07 287.21 Min: 286.53 Max: 288.85 Mean: 287.35 Std Dev: 0.79 after: Run times: 289.58 287.40 286.97 287.20 287.01 Min: 286.97 Max: 289.58 Mean: 287.63 Std Dev: 0.99 Delta: 0.1% which is well below the standard deviation [1] https://github.com/ThomasKing2014/slides/raw/master/Building%20universal%20Android%20rooting%20with%20a%20type%20confusion%20vulnerability.pdf Link: http://lkml.kernel.org/r/20190530045017.15252-2-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Alexander Popov <alex.popov@linux.com> Cc: Alexander Potapenko <glider@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@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 Restructured Text 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.