powerpc/tm: Fix null pointer deference in flush_hash_page

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

Signed-off-by: Michael Neuling <mikey@neuling.org>
Reported-by: John J Miller <millerjo@us.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 3e4c4ed19335..88ac0eeaadde 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -1230,6 +1230,7 @@ void flush_hash_page(unsigned long vpn, real_pte_t pte, int psize, int ssize,
          * 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);