gsm_7bit_decode: Handle the case of the last charachter being an escape

If i + 1 == length and it is an escape charachter we would try
to read rtext[length] which is one after the field we have allocated.

diff --git a/src/gsm_utils.c b/src/gsm_utils.c
index fb69377..3a378ac 100644 (file)
--- a/src/gsm_utils.c
+++ b/src/gsm_utils.c
@@ -65,7 +65,7 @@ int gsm_7bit_decode(char *text, const uint8_t *user_data, uint8_t length)
        }
        for(i = 0; i < length; i++){
                /* this is an extension character */
-               if(rtext[i] == 0x1b){
+               if(rtext[i] == 0x1b && i + 1 < length){
                        tmp = rtext[i+1];
                        *(text++) = gsm_7bit_alphabet[0x7f + tmp];
                        i++;