At conditional (3): "key_len > 64UL" taking the false branch.
57    if (key_len > HMAC_SHA1_BLOCKSIZE) {
58        /* keys longer than blocksize are shortened */
59        HASH_Begin(sha1);
60        HASH_Update(sha1, key, key_len);
61        HASH_End(sha1, ikey, &res_len, SSS_SHA1_LENGTH);
62        memset(ikey + SSS_SHA1_LENGTH, 0, HMAC_SHA1_BLOCKSIZE - SSS_SHA1_LENGTH);
63    } else {
64        /* keys shorter than blocksize are zero-padded */
65        memcpy(ikey, key, key_len);
CID 12623: Out-of-bounds read (OVERRUN_STATIC)Overrunning static array of size 64 bytes at byte position 64 by accessing with pointer "&ikey[key_len]" through dereference in call to "memset". (The dereference is assumed on the basis of the 'nonnull' parameter attribute.)
Note: These bugs are often difficult to see at first glance. Coverity recommends a close inspection of the events leading to this overrun.
66        memset(ikey + key_len, 0, HMAC_SHA1_BLOCKSIZE - key_len);
67    }