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Vivian Wang
7643e56229
commit8d6c8c40e7upstream. In kfence_protect_page(), which kfence_unprotect() calls, we cannot send IPIs to other CPUs to ask them to flush TLB. This may lead to those CPUs spuriously faulting on a recently allocated kfence object despite it being valid, leading to false positive use-after-free reports. Fix this by calling mark_new_valid_map() so that the page fault handling code path notices the spurious fault and flushes TLB then retries the access. Update the comment in handle_exception to indicate that new_valid_map_cpus_check also handles kfence_unprotect() spurious faults. Note that kfence_protect() has the same stale TLB entries problem, but that leads to false negatives, which is fine with kfence. Cc: stable@vger.kernel.org Reported-by: Yanko Kaneti <yaneti@declera.com> Fixes:b3431a8bb3("riscv: Fix IPIs usage in kfence_protect_page()") Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn> Link: https://patch.msgid.link/20260303-handle-kfence-protect-spurious-fault-v2-2-f80d8354d79d@iscas.ac.cn Signed-off-by: Paul Walmsley <pjw@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.