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In commit2865d08dd9("powerpc/mm: Move the DSISR_PROTFAULT sanity check") we moved the protection fault access check before the vma lookup. That means we hit that WARN_ON when user space accesses a kernel address. Before that commit this was handled by find_vma() not finding vma for the kernel address and considering that access as bad area access. Avoid the confusing WARN_ON and convert that to a ratelimited printk. With the patch we now get: for load: a.out[5997]: User access of kernel address (c00000000000dea0) - exploit attempt? (uid: 1000) a.out[5997]: segfault (11) at c00000000000dea0 nip 1317c0798 lr 7fff80d6441c code 1 in a.out[1317c0000+10000] a.out[5997]: code: 60000000 60420000 3c4c0002 38427790 4bffff20 3c4c0002 38427784 fbe1fff8 a.out[5997]: code: f821ffc1 7c3f0b78 60000000 e9228030 <89290000> 993f002f 60000000 383f0040 for exec: a.out[6067]: User access of kernel address (c00000000000dea0) - exploit attempt? (uid: 1000) a.out[6067]: segfault (11) at c00000000000dea0 nip c00000000000dea0 lr 129d507b0 code 1 a.out[6067]: Bad NIP, not dumping instructions. Fixes:2865d08dd9("powerpc/mm: Move the DSISR_PROTFAULT sanity check") Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Tested-by: Breno Leitao <leitao@debian.org> [mpe: Don't split printk() string across lines] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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.