Checked the number of subauthorities before accessing them

Be more crash resistent when analyzing a badly formed SID.
(contributed by Ulf Zibis)

diff --git a/ntfsprogs/ntfssecaudit.c b/ntfsprogs/ntfssecaudit.c
index cde4477..b243bad 100644 (file)
--- a/ntfsprogs/ntfssecaudit.c
+++ b/ntfsprogs/ntfssecaudit.c
@@ -971,10 +971,11 @@ static void showsid(const char *attr, int off, const char *prefix, int level)
                marker = ' ';
        cnt = attr[off+1] & 255;
        auth = get6h(attr,off+2);
-       first = get4l(attr,off+8);
        known = FALSE;
        if ((attr[off] == 1) /* revision */
-            && (auth < 100))
+            && cnt
+            && (auth < 100)) {
+               first = get4l(attr,off+8);
                switch (cnt) {
                case 0 : /* no level (error) */
                        break;
@@ -1105,6 +1106,7 @@ static void showsid(const char *attr, int off, const char *prefix, int level)
                                break;
                        }
                }
+       }
        if (!known)
                printf("%*cUnknown SID\n",-level,marker);
        printf("%*c%shex S-%d-",-level,marker,prefix,attr[off] & 255);