tree c7c16937d854a908e7a9f577e972cc55e39bbae6
parent 3da793857d78142e3594c67f4405ad19b57e9cd1
author Vadim Yanitskiy <axilirator@gmail.com> 1516402363 +0600
committer Harald Welte <laforge@gnumonks.org> 1516617353 +0000

tests/ussd: prevent uninitialized memory access

Previously an incorrect length value was passed to both
gsm_7bit_decode_n_ussd() and gsm_7bit_encode_n_ussd()
functions during test_7bit_ussd() execution, due to:

   octets_written = strlen(decoded);

The problem is that a 7-bit encoded string takes less memory
than its 8-bit equivalent. So, here strlen() returns one-byte
bigger value, that octets_written is. This then causes the
uninitialized memory access.

Found using Valgrind:

Conditional jump or move depends on uninitialised value(s)
   at 0x506DCCC: gsm_7bit_decode_n_ussd (gsm_utils.c:248)
   by 0x40134B: test_7bit_ussd (ussd_test.c:104)
   by 0x400F5D: main (ussd_test.c:161)

Conditional jump or move depends on uninitialised value(s)
   at 0x506DBB7: gsm_7bit_decode_n_hdr (gsm_utils.c:220)
   by 0x506DC9E: gsm_7bit_decode_n_ussd (gsm_utils.c:246)
   by 0x40134B: test_7bit_ussd (ussd_test.c:104)
   by 0x400F5D: main (ussd_test.c:161)

Conditional jump or move depends on uninitialised value(s)
   at 0x506DBCB: gsm_septet_lookup (gsm_utils.c:153)
   by 0x506DBCB: gsm_7bit_decode_n_hdr (gsm_utils.c:224)
   by 0x506DC9E: gsm_7bit_decode_n_ussd (gsm_utils.c:246)
   by 0x40134B: test_7bit_ussd (ussd_test.c:104)
   by 0x400F5D: main (ussd_test.c:161)

Change-Id: Ic31805b6a5a917dfc6284edba6ffdd21246ac20c