fix possible null ptr deref in kallsyms_lookup

ugh, this function gets called by our unwinder. recursive backtrace for
the win... bisection to find this one was "fun."

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index f1bda23140b2..fed54418626c 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -257,7 +257,8 @@ const char *kallsyms_lookup(unsigned long addr,
                 pos = get_symbol_pos(addr, symbolsize, offset);
                 /* Grab name */
                 kallsyms_expand_symbol(get_symbol_offset(pos), namebuf);
-                *modname = NULL;
+                if (modname)
+                        *modname = NULL;
                 return namebuf;
         }