Fix faulty check of padding in x_long.c

[openssl.git] / crypto / asn1 / x_long.c

diff --git a/crypto/asn1/x_long.c b/crypto/asn1/x_long.c
index 0af78752018843bcdf780db623796be3b62ec934..a7b90231c0e6f790158cd0e807779630ee8e340e 100644 (file)
--- a/crypto/asn1/x_long.c
+++ b/crypto/asn1/x_long.c
@@ -76,7 +76,7 @@ static int long_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
      * set.
      */
     if (ltmp < 0)
-        utmp = -ltmp - 1;
+        utmp = 0 - (unsigned long)ltmp - 1;
     else
         utmp = ltmp;
     clen = BN_num_bits_word(utmp);
@@ -105,19 +105,44 @@ static int long_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
 static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
                     int utype, char *free_cont, const ASN1_ITEM *it)
 {
-    int neg, i;
+    int neg = -1, i;
     long ltmp;
     unsigned long utmp = 0;
     char *cp = (char *)pval;
+
+    if (len > 1) {
+        /*
+         * Check possible pad byte.  Worst case, we're skipping past actual
+         * content, but since that's only with 0x00 and 0xff and we set neg
+         * accordingly, the result will be correct in the end anyway.
+         */
+        switch (cont[0]) {
+        case 0xff:
+            cont++;
+            len--;
+            neg = 0x80;
+            break;
+        case 0:
+            cont++;
+            len--;
+            neg = 0;
+            break;
+        }
+    }
     if (len > (int)sizeof(long)) {
         ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
         return 0;
     }
-    /* Is it negative? */
-    if (len && (cont[0] & 0x80))
-        neg = 1;
-    else
-        neg = 0;
+    if (neg == -1) {
+        /* Is it negative? */
+        if (len && (cont[0] & 0x80))
+            neg = 1;
+        else
+            neg = 0;
+    } else if (neg == (cont[0] & 0x80)) {
+        ASN1err(ASN1_F_LONG_C2I, ASN1_R_ILLEGAL_PADDING);
+        return 0;
+    }
     utmp = 0;
     for (i = 0; i < len; i++) {
         utmp <<= 8;
@@ -127,6 +152,10 @@ static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
             utmp |= cont[i];
     }
     ltmp = (long)utmp;
+    if (ltmp < 0) {
+        ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
+        return 0;
+    }
     if (neg) {
         ltmp = -ltmp;
         ltmp--;