Blackfin: make sure stack is accessible before dumping it

When displaying a crash dump, make sure accessing the stack is safe so
we don't crash at the same time.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/blackfin/kernel/traps.c b/arch/blackfin/kernel/traps.c
index fb5774275889..0d04a4732b1f 100644
--- a/arch/blackfin/kernel/traps.c
+++ b/arch/blackfin/kernel/traps.c
@@ -196,6 +196,11 @@ done:
 
 asmlinkage void double_fault_c(struct pt_regs *fp)
 {
+#ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
+        int j;
+        trace_buffer_save(j);
+#endif
+
         console_verbose();
         oops_in_progress = 1;
 #ifdef CONFIG_DEBUG_VERBOSE
@@ -220,6 +225,7 @@ asmlinkage void double_fault_c(struct pt_regs *fp)
                 dump_bfin_process(fp);
                 dump_bfin_mem(fp);
                 show_regs(fp);
+                dump_bfin_trace_buffer();
         }
 #endif
         panic("Double Fault - unrecoverable event");
@@ -832,6 +838,11 @@ void show_stack(struct task_struct *task, unsigned long *stack)
         decode_address(buf, (unsigned int)stack);
         printk(KERN_NOTICE " SP: [0x%p] %s\n", stack, buf);
 
+        if (!access_ok(VERIFY_READ, stack, (unsigned int)endstack - (unsigned int)stack)) {
+                printk(KERN_NOTICE "Invalid stack pointer\n");
+                return;
+        }
+
         /* First thing is to look for a frame pointer */
         for (addr = (unsigned int *)((unsigned int)stack & ~0xF); addr < endstack; addr++) {
                 if (*addr & 0x1)