powerpc/pkeys: Fix handling of pkey state across fork()
[ Upstream commit 2cd4bd192ee94848695c1c052d87913260e10f36 ] Protection key tracking information is not copied over to the mm_struct of the child during fork(). This can cause the child to erroneously allocate keys that were already allocated. Any allocated execute-only key is lost aswell. Add code; called by dup_mmap(), to copy the pkey state from parent to child explicitly. This problem was originally found by Dave Hansen on x86, which turns out to be a problem on powerpc aswell. Fixes: cf43d3b2 ("powerpc: Enable pkey subsystem") Cc: stable@vger.kernel.org # v4.16+ Reviewed-by: NThiago Jung Bauermann <bauerman@linux.ibm.com> Signed-off-by: NRam Pai <linuxram@us.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au> Signed-off-by: NSasha Levin <sashal@kernel.org>
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