gsm_7bit_encode_n(): fix integer overflow in gsm_septets2octets()

Using 'uint8_t' for the length argument is definitely a bad idea.
Because of this, packing more than 255 septets would not work as
expected.  Deprecate the old function and use 'size_t' instead.

Change-Id: Ib1aac538afeb0a5c76a1df472d555139a496e12e

1 files changed, 4 insertions, 1 deletions

diff --git a/include/osmocom/gsm/gsm_utils.h b/include/osmocom/gsm/gsm_utils.h
index de634348..0909006e 100644
--- a/include/osmocom/gsm/gsm_utils.h
+++ b/include/osmocom/gsm/gsm_utils.h
@@ -110,7 +110,10 @@ int gsm_7bit_encode_n(uint8_t *result, size_t n, const char *data, int *octets_w
 int gsm_7bit_encode_n_ussd(uint8_t *result, size_t n, const char *data, int *octets_written);
 
 /* the four functions below are helper functions and here for the unit test */
-int gsm_septets2octets(uint8_t *result, const uint8_t *rdata, uint8_t septet_len, uint8_t padding);
+int gsm_septets2octets(uint8_t *result, const uint8_t *rdata, uint8_t septet_len, uint8_t padding)
+	OSMO_DEPRECATED("This function is unable to handle more than 255 septets, "
+			"use gsm_septet_pack() instead.");
+int gsm_septet_pack(uint8_t *result, const uint8_t *rdata, size_t septet_len, uint8_t padding);
 int gsm_septet_encode(uint8_t *result, const char *data);
 uint8_t gsm_get_octet_len(const uint8_t sept_len);
 int gsm_7bit_decode_n_hdr(char *decoded, size_t n, const uint8_t *user_data, uint8_t length, uint8_t ud_hdr_ind);