[PATCH] unwinder: more sanity checks in Dwarf2 unwinder

Tighten the requirements on both input to and output from the Dwarf2
unwinder.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 9864d195c408..4fdd162f0bef 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -225,12 +225,19 @@ static int dump_trace_unwind(struct unwind_frame_info *info, void *context)
 {
         struct ops_and_data *oad = (struct ops_and_data *)context;
         int n = 0;
+        unsigned long sp = UNW_SP(info);
 
+        if (arch_unw_user_mode(info))
+                return -1;
         while (unwind(info) == 0 && UNW_PC(info)) {
                 n++;
                 oad->ops->address(oad->data, UNW_PC(info));
                 if (arch_unw_user_mode(info))
                         break;
+                if ((sp & ~(PAGE_SIZE - 1)) == (UNW_SP(info) & ~(PAGE_SIZE - 1))
+                    && sp > UNW_SP(info))
+                        break;
+                sp = UNW_SP(info);
         }
         return n;
 }