udhcpc: fix segmentation fault on empty bin opt

The following caused udhcpc to segfault:
  busybox udhcpc -i lo -s /dev/null -x 0x3d:

function                                             old     new   delta
udhcp_str2optset                                     629     641     +12

Signed-off-by: Michal Kazior <michal@plume.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
index 4a452cdb9..9ec752dfc 100644
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -539,7 +539,7 @@ int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg,
 
                 if (optflag->flags == OPTION_BIN) {
                         val = strtok(NULL, ""); /* do not split "'q w e'" */
-                        trim(val);
+                        if (val) trim(val);
                 } else
                         val = strtok(NULL, ", \t");
                 if (!val)