[ 03/73] powerpc/tm: Fix null pointer deference in flush_hash_page

[Greg Kroah-Hartman]

3.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Neuling <mikey@xxxxxxxxxxx>

commit c2fd22df89365df9451d5b91da3b7bfd48122ecd upstream.

Make sure that current->thread.reg exists before we deference it in
flush_hash_page.

Signed-off-by: Michael Neuling <mikey@xxxxxxxxxxx>
Reported-by: John J Miller <millerjo@xxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/powerpc/mm/hash_utils_64.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -1191,6 +1191,7 @@ void flush_hash_page(unsigned long vpn,
 	 * unmapping it first, it may see the speculated version.
 	 */
 	if (local && cpu_has_feature(CPU_FTR_TM) &&
+	    current->thread.regs &&
 	    MSR_TM_ACTIVE(current->thread.regs->msr)) {
 		tm_enable();
 		tm_abort(TM_CAUSE_TLBI);


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