MIPS: Fix Magic SysRq L kernel crash.

show_backtrace() was passed a NULL pointer which caused paging
request fail. Set to current task as other architectures (ARM,
etc) do when passed a NULL task pointer.

Signed-off-by: Vincent Wen <vincentwenlinux@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: cernekee@gmail.com
Patchwork: https://patchwork.linux-mips.org/patch/3524/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index ce95f2c41f3f..9716f057a77b 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -132,6 +132,9 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs)
         unsigned long ra = regs->regs[31];
         unsigned long pc = regs->cp0_epc;
 
+        if (!task)
+                task = current;
+
         if (raw_show_trace || !__kernel_text_address(pc)) {
                 show_raw_backtrace(sp);
                 return;