4.18-stable review patch. If anyone has any objections, please let me know.
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From: Thiago Jung Bauermann bauerman@linux.ibm.com
commit c716a25b9b70084e1144f77423f5aedd772ea478 upstream.
scan_pkey_feature() uses of_property_read_u32_array() to read the ibm,processor-storage-keys property and calls be32_to_cpu() on the value it gets. The problem is that of_property_read_u32_array() already returns the value converted to the CPU byte order.
The value of pkeys_total ends up more or less sane because there's a min() call in pkey_initialize() which reduces pkeys_total to 32. So in practice the kernel ignores the fact that the hypervisor reserved one key for itself (the device tree advertises 31 keys in my test VM).
This is wrong, but the effect in practice is that when a process tries to allocate the 32nd key, it gets an -EINVAL error instead of -ENOSPC which would indicate that there aren't any keys available
Fixes: cf43d3b26452 ("powerpc: Enable pkey subsystem") Cc: stable@vger.kernel.org # v4.16+ Signed-off-by: Thiago Jung Bauermann bauerman@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/mm/pkeys.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -44,7 +44,7 @@ static void scan_pkey_feature(void) * Since any pkey can be used for data or execute, we will just treat * all keys as equal and track them as one entity. */ - pkeys_total = be32_to_cpu(vals[0]); + pkeys_total = vals[0]; pkeys_devtree_defined = true; }