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a7cb5d23ea
Originally the addr != NULL check was meant to take care of the case
where __kfence_pool == NULL (KFENCE is disabled). However, this does
not work for addresses where addr > 0 && addr < KFENCE_POOL_SIZE.
This can be the case on NULL-deref where addr > 0 && addr < PAGE_SIZE or
any other faulting access with addr < KFENCE_POOL_SIZE. While the
kernel would likely crash, the stack traces and report might be
confusing due to double faults upon KFENCE's attempt to unprotect such
an address.
Fix it by just checking that __kfence_pool != NULL instead.
Link: https://lkml.kernel.org/r/20210818130300.2482437-1-elver@google.com
Fixes: 0ce20dd840 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Marco Elver <elver@google.com>
Reported-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org> [5.12+]
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.