libceph: fix undefined behavior when using snprintf()
authorCong Ding <dinggnu@gmail.com>
Fri, 25 Jan 2013 23:48:59 +0000 (17:48 -0600)
committerAlex Elder <elder@inktank.com>
Fri, 25 Jan 2013 23:48:59 +0000 (17:48 -0600)
The variable "str" is used as both the source and destination in
function snprintf(), which is undefined behavior based on C11. The
original description in C11 is:
"If copying takes place between objects that
overlap, the behavior is undefined."

And, the function of ceph_osdmap_state_str() is to return the osdmap
state, so it should return "doesn't exist" when all the conditions
are not satisfied. I fix it in this patch.

[elder@inktank.com: shortened the commit message]

Signed-off-by: Cong Ding <dinggnu@gmail.com>
Reviewed-by: Alex Elder <elder@inktank.com>
net/ceph/osdmap.c

index 369f03ba9ee53b5bba477eebb3d0f9932b9544b8..3c61e21611d3c5a5e666c9bf6c46126ea95f927b 100644 (file)
 
 char *ceph_osdmap_state_str(char *str, int len, int state)
 {
-       int flag = 0;
-
        if (!len)
-               goto done;
-
-       *str = '\0';
-       if (state) {
-               if (state & CEPH_OSD_EXISTS) {
-                       snprintf(str, len, "exists");
-                       flag = 1;
-               }
-               if (state & CEPH_OSD_UP) {
-                       snprintf(str, len, "%s%s%s", str, (flag ? ", " : ""),
-                                "up");
-                       flag = 1;
-               }
-       } else {
+               return str;
+
+       if ((state & CEPH_OSD_EXISTS) && (state & CEPH_OSD_UP))
+               snprintf(str, len, "exists, up");
+       else if (state & CEPH_OSD_EXISTS)
+               snprintf(str, len, "exists");
+       else if (state & CEPH_OSD_UP)
+               snprintf(str, len, "up");
+       else
                snprintf(str, len, "doesn't exist");
-       }
-done:
+
        return str;
 }