[PATCH] rpcinfo: stack buffer overflow in rpcinfo rpcbdump()

[Krzesimir Nowak <qdlacz@gmail.com>]

rpcinfo's rpcbdump() formats a server-controlled list of versions into
a fixed size buffer with sprintf(). A malicious server returning a
large number of versions may overflow it.

Reported-by: Michalis Vasileiadis <vmihalis.tmd@gmail.com>
Signed-off-by: Krzesimir Nowak <knowak@microsoft.com>
---
 src/rpcinfo.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/rpcinfo.c b/src/rpcinfo.c
index 30d535e..9917913 100644
--- a/src/rpcinfo.c
+++ b/src/rpcinfo.c
@@ -958,17 +958,19 @@ rpcbdump (
       for (rs = rs_head; rs; rs = rs->next)
 	{
 	  size_t netidmax = sizeof(buf) - 1;
-	  char *p = buf;
+	  int l = 0;
 
 	  printf ("%10ld  ", rs->prog);
 	  for (vl = rs->vlist; vl; vl = vl->next)
 	    {
-	      sprintf (p, "%d", vl->vers);
-	      p = p + strlen (p);
+	      l += printf ("%d", vl->vers);
 	      if (vl->next)
-		sprintf (p++, ",");
+		l += printf (",");
 	    }
-	  printf ("%-10s", buf);
+	  if (l < 10)
+	    printf("%*s", 10 - l, " ");
+	  else
+	    printf(" ");
 	  buf[0] = '\0';
 
           for (nl = rs->nlist; nl; nl = nl->next)
-- 
2.54.0