powerpc/pkeys: Preallocate execute-only key

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execute-only key is allocated dynamically. This is a problem. When a
thread implicitly creates an execute-only key, and resets the UAMOR
for that key, the UAMOR value does not percolate to all the other
threads. Any other thread may ignorantly change the permissions on the
key. This can cause the key to be not execute-only for that thread.

Preallocate the execute-only key and ensure that no thread can change
the permission of the key, by resetting the corresponding bit in
UAMOR.

Fixes: 5586cf61e1 ("powerpc: introduce execute-only pkey")
Cc: stable@vger.kernel.org # v4.16+
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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Ram Pai 2018-07-17 06:51:07 -07:00 • committed by Michael Ellerman

parent fe6a2804e6

commit a4fcc877d4

1 changed files with 18 additions and 45 deletions

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arch/powerpc/mm/pkeys.c

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