sparc64: Fix end-of-stack checking in save_stack_trace().

Bug reported by Alexander Beregalov.

Before we dereference the stack frame or try to peek at the
pt_regs magic value, make sure the entire object is within
the kernel stack bounds.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/sparc64/kernel/stacktrace.c b/arch/sparc64/kernel/stacktrace.c
index b3e3737750d8..e9d7f0660f2e 100644
--- a/arch/sparc64/kernel/stacktrace.c
+++ b/arch/sparc64/kernel/stacktrace.c
@@ -26,13 +26,15 @@ void save_stack_trace(struct stack_trace *trace)
 
                 /* Bogus frame pointer? */
                 if (fp < (thread_base + sizeof(struct thread_info)) ||
-                    fp >= (thread_base + THREAD_SIZE))
+                    fp > (thread_base + THREAD_SIZE - sizeof(struct sparc_stackf)))
                         break;
 
                 sf = (struct sparc_stackf *) fp;
                 regs = (struct pt_regs *) (sf + 1);
 
-                if ((regs->magic & ~0x1ff) == PT_REGS_MAGIC) {
+                if (((unsigned long)regs <=
+                     (thread_base + THREAD_SIZE - sizeof(*regs))) &&
+                    (regs->magic & ~0x1ff) == PT_REGS_MAGIC) {
                         if (!(regs->tstate & TSTATE_PRIV))
                                 break;
                         pc = regs->tpc;