58fa4b36ab
[ Upstream commit 6039ca254979694c5362dfebadd105e286c397bb ] The pkey test code keeps a "shadow" of the pkey register around. This ensures that any bugs which might write to the register can be caught more quickly. Generally, userspace has a good idea when the kernel is going to write to the register. For instance, alloc_pkey() is passed a permission mask. The caller of alloc_pkey() can update the shadow based on the return value and the mask. But, the kernel can also modify the pkey register in a more sneaky way. For mprotect(PROT_EXEC) mappings, the kernel will allocate a pkey and write the pkey register to create an execute-only mapping. The kernel never tells userspace what key it uses for this. This can cause the test to fail with messages like: protection_keys_64.2: pkey-helpers.h:132: _read_pkey_reg: Assertion `pkey_reg == shadow_pkey_reg' failed. because the shadow was not updated with the new kernel-set value. Forcibly update the shadow value immediately after an mprotect(). Link: https://lkml.kernel.org/r/20210611164200.EF76AB73@viggo.jf.intel.com Fixes: 6af17cf89e99 ("x86/pkeys/selftests: Add PROT_EXEC test") Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Ram Pai <linuxram@us.ibm.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Florian Weimer <fweimer@redhat.com> Cc: "Desnes A. Nunes do Rosario" <desnesn@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Suchanek <msuchanek@suse.de> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.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.