SMB: Add two missing bounds checks

[tcpdump] / smbutil.c

diff --git a/smbutil.c b/smbutil.c
index 69d29c66ccc56881bc5e2ddab3e0298a9fa3b0b5..527f31a47874cf4ed32157262becf00ec2874f76 100644 (file)
--- a/smbutil.c
+++ b/smbutil.c
@@ -20,9 +20,20 @@
 #include "extract.h"
 #include "smb.h"
 
+static int stringlen_is_set;
 static uint32_t stringlen;
 extern const u_char *startbuf;
 
+/*
+ * Reset SMB state.
+ */
+void
+smb_reset(void)
+{
+    stringlen_is_set = 0;
+    stringlen = 0;
+}
+
 /*
  * interpret a 32 bit dos packed date/time to some parameters
  */
@@ -340,15 +351,14 @@ write_bits(netdissect_options *ndo,
 
 /* convert a UCS-2 string into an ASCII string */
 #define MAX_UNISTR_SIZE        1000
-static int
+static const u_char *
 unistr(netdissect_options *ndo, char (*buf)[MAX_UNISTR_SIZE+1],
-       const u_char *s, uint32_t *len, int is_null_terminated, int use_unicode)
+       const u_char *s, uint32_t strsize, int is_null_terminated,
+       int use_unicode)
 {
     u_int c;
     size_t l = 0;
-    uint32_t strsize;
     const u_char *sp;
-    int padding = 0;
 
     if (use_unicode) {
        /*
@@ -357,7 +367,6 @@ unistr(netdissect_options *ndo, char (*buf)[MAX_UNISTR_SIZE+1],
        if (((s - startbuf) % 2) != 0) {
            ND_TCHECK_1(s);
            s++;
-           padding++;
        }
     }
     if (is_null_terminated) {
@@ -370,29 +379,22 @@ unistr(netdissect_options *ndo, char (*buf)[MAX_UNISTR_SIZE+1],
        if (!use_unicode) {
            for (;;) {
                ND_TCHECK_1(sp);
-               *len += 1;
-               if (GET_U_1(sp) == 0)
-                   break;
+               c = GET_U_1(sp);
                sp++;
+               strsize++;
+               if (c == '\0')
+                   break;
            }
-           strsize = *len - 1;
        } else {
            for (;;) {
                ND_TCHECK_2(sp);
-               *len += 2;
-               if (GET_U_1(sp) == 0 && GET_U_1(sp + 1) == 0)
-                   break;
+               c = GET_LE_U_2(sp);
                sp += 2;
+               strsize += 2;
+               if (c == '\0')
+                   break;
            }
-           strsize = *len - 2;
        }
-       *len += padding;
-    } else {
-       /*
-        * Counted string.
-        */
-       strsize = *len;
-       *len += padding;
     }
     if (!use_unicode) {
        while (strsize != 0) {
@@ -411,6 +413,8 @@ unistr(netdissect_options *ndo, char (*buf)[MAX_UNISTR_SIZE+1],
                 * skipping past it.
                 */
                ND_TCHECK_LEN(s, strsize);
+               s += strsize;
+               strsize = 0;
                break;
            }
            if (l < MAX_UNISTR_SIZE) {
@@ -441,6 +445,8 @@ unistr(netdissect_options *ndo, char (*buf)[MAX_UNISTR_SIZE+1],
                 * skipping past it.
                 */
                ND_TCHECK_LEN(s, strsize);
+               s += strsize;
+               strsize = 0;
                break;
            }
            if (l < MAX_UNISTR_SIZE) {
@@ -461,11 +467,11 @@ unistr(netdissect_options *ndo, char (*buf)[MAX_UNISTR_SIZE+1],
        }
     }
     (*buf)[l] = 0;
-    return 0;
+    return s;
 
 trunc:
     (*buf)[l] = 0;
-    return -1;
+    return NULL;
 }
 
 static const u_char *
@@ -649,6 +655,7 @@ smb_fdata1(netdissect_options *ndo,
            case 'b':
                ND_TCHECK_1(buf);
                stringlen = GET_U_1(buf);
+               stringlen_is_set = 1;
                ND_PRINT("%u", stringlen);
                buf += 1;
                break;
@@ -658,6 +665,7 @@ smb_fdata1(netdissect_options *ndo,
                ND_TCHECK_2(buf);
                stringlen = reverse ? GET_BE_U_2(buf) :
                                      GET_LE_U_2(buf);
+               stringlen_is_set = 1;
                ND_PRINT("%u", stringlen);
                buf += 2;
                break;
@@ -667,6 +675,7 @@ smb_fdata1(netdissect_options *ndo,
                ND_TCHECK_4(buf);
                stringlen = reverse ? GET_BE_U_4(buf) :
                                      GET_LE_U_4(buf);
+               stringlen_is_set = 1;
                ND_PRINT("%u", stringlen);
                buf += 4;
                break;
@@ -678,35 +687,25 @@ smb_fdata1(netdissect_options *ndo,
        case 'R':       /* like 'S', but always ASCII */
          {
            /*XXX unistr() */
-           uint32_t len;
-           int result;
-
-           len = 0;
-           result = unistr(ndo, &strbuf, buf, &len, 1, (*fmt == 'R') ? 0 : unicodestr);
+           buf = unistr(ndo, &strbuf, buf, 0, 1, (*fmt == 'R') ? 0 : unicodestr);
            ND_PRINT("%s", strbuf);
-           if (result == -1)
+           if (buf == NULL)
                goto trunc;
-           buf += len;
            fmt++;
            break;
          }
        case 'Z':
        case 'Y':       /* like 'Z', but always ASCII */
          {
-           uint32_t len;
-           int result;
-
            ND_TCHECK_1(buf);
            if (GET_U_1(buf) != 4 && GET_U_1(buf) != 2) {
                ND_PRINT("Error! ASCIIZ buffer of type %u", GET_U_1(buf));
                return maxbuf;  /* give up */
            }
-           len = 0;
-           result = unistr(ndo, &strbuf, buf + 1, &len, 1, (*fmt == 'Y') ? 0 : unicodestr);
+           buf = unistr(ndo, &strbuf, buf + 1, 0, 1, (*fmt == 'Y') ? 0 : unicodestr);
            ND_PRINT("%s", strbuf);
-           if (result == -1)
+           if (buf == NULL)
                goto trunc;
-           buf += len + 1;
            fmt++;
            break;
          }
@@ -723,6 +722,10 @@ smb_fdata1(netdissect_options *ndo,
          }
        case 'c':
          {
+            if (!stringlen_is_set) {
+                ND_PRINT("{stringlen not set}");
+                goto trunc;
+            }
            ND_TCHECK_LEN(buf, stringlen);
            ND_PRINT("%-*.*s", (int)stringlen, (int)stringlen, buf);
            buf += stringlen;
@@ -733,13 +736,14 @@ smb_fdata1(netdissect_options *ndo,
          }
        case 'C':
          {
-           int result;
-
-           result = unistr(ndo, &strbuf, buf, &stringlen, 0, unicodestr);
+            if (!stringlen_is_set) {
+                ND_PRINT("{stringlen not set}");
+                goto trunc;
+            }
+           buf = unistr(ndo, &strbuf, buf, stringlen, 0, unicodestr);
            ND_PRINT("%s", strbuf);
-           if (result == -1)
+           if (buf == NULL)
                goto trunc;
-           buf += stringlen;
            fmt++;
            break;
          }