[openssl-commits] [openssl] OpenSSL_1_1_0-stable update

[Richard Levitte]

The branch OpenSSL_1_1_0-stable has been updated
       via  249452df67f7a5e4b203d71837cc0e8a31d62c75 (commit)
      from  201eb73cfdbdb744a8ef767e481ac42436650f41 (commit)


- Log -----------------------------------------------------------------
commit 249452df67f7a5e4b203d71837cc0e8a31d62c75
Author: Richard Levitte <levitte at openssl.org>
Date:   Mon Mar 20 21:31:02 2017 +0100

    Fix decoding of ASN.1 LONG and ZLONG items
    
    LONG and ZLONG items (which are OpenSSL private special cases of
    ASN1_INTEGER) are encoded into DER with padding if the leading octet
    has the high bit set, where the padding can be 0x00 (for positive
    numbers) or 0xff (for negative ones).
    
    When decoding DER to LONG or ZLONG, the padding wasn't taken in
    account at all, which means that if the encoded size with padding
    is one byte more than the size of long, decoding fails.  This change
    fixes that issue.
    
    Reviewed-by: Rich Salz <rsalz at openssl.org>
    (Merged from https://github.com/openssl/openssl/pull/3000)

-----------------------------------------------------------------------

Summary of changes:
 crypto/asn1/x_long.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/crypto/asn1/x_long.c b/crypto/asn1/x_long.c
index c284471..233725f 100644
--- a/crypto/asn1/x_long.c
+++ b/crypto/asn1/x_long.c
@@ -105,19 +105,41 @@ 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) {
+        /*
+         * 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 = 1;
+            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;
+    }
     utmp = 0;
     for (i = 0; i < len; i++) {
         utmp <<= 8;