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powerpc/pkeys: Detach execute_only key on !PROT_EXEC 

Disassociate the exec_key from a VMA if the VMA permission is not
PROT_EXEC anymore. Otherwise the exec_only key continues to be
associated with the vma, causing unexpected behavior.

The problem was reported on x86 by Shakeel Butt, which is also
applicable on powerpc.

Fixes: 5586cf61e1 ("powerpc: introduce execute-only pkey")
Cc: stable@vger.kernel.org # v4.16+
Reported-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Ram Pai 2018-05-04 13:01:51 -07:00 committed by Michael Ellerman
parent 7574364906
commit eabdb8ca86
1 changed files with 2 additions and 2 deletions
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4
arch/powerpc/mm/pkeys.c
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@ -383,9 +383,9 @@ int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot,
{
/*
* If the currently associated pkey is execute-only, but the requested
* protection requires read or write, move it back to the default pkey.
* protection is not execute-only, move it back to the default pkey.
*/
if (vma_is_pkey_exec_only(vma) && (prot & (PROT_READ | PROT_WRITE)))
if (vma_is_pkey_exec_only(vma) && (prot != PROT_EXEC))
return 0;
/*