powerpc/pkeys: Fix handling of pkey state across fork()

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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: cf43d3b264 ("powerpc: Enable pkey subsystem")
Cc: stable@vger.kernel.org # v4.16+
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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Ram Pai 2018-12-20 12:03:30 -08:00 • committed by Michael Ellerman

parent 2f07229f02

commit 2cd4bd192e

2 changed files with 19 additions and 6 deletions

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15

arch/powerpc/include/asm/mmu_context.h

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10

arch/powerpc/mm/pkeys.c

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