1 files changed, 11 insertions, 0 deletions

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index cbab1df150cf..017290241261 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -825,6 +825,17 @@ int vsscanf(const char * buf, const char * fmt, va_list args)
                         break;
                 str = next;
         }
+
+        /*
+         * Now we've come all the way through so either the input string or the
+         * format ended. In the former case, there can be a %n at the current
+         * position in the format that needs to be filled.
+         */
+        if (*fmt == '%' && *(fmt + 1) == 'n') {
+                int *p = (int *)va_arg(args, int *);
+                *p = str - buf;
+        }
+
         return num;
 }