[PATCH] libosmocore[master]: tests/ussd: prevent uninitialized memory access

[Vadim Yanitskiy]

Hello Jenkins Builder,

I'd like you to reexamine a change.  Please visit

    https://gerrit.osmocom.org/5934

to look at the new patch set (#2).

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
---
M tests/ussd/ussd_test.c
1 file changed, 1 insertion(+), 2 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/34/5934/2

diff --git a/tests/ussd/ussd_test.c b/tests/ussd/ussd_test.c
index 8d88dbb..429c72d 100644
--- a/tests/ussd/ussd_test.c
+++ b/tests/ussd/ussd_test.c
@@ -90,8 +90,7 @@
 	OSMO_ASSERT(strcmp(encoded_hex, osmo_hexdump_nospc(coded, octets_written)) == 0);
 
 	gsm_7bit_decode_n_ussd(decoded, sizeof(decoded), coded, octets_written * 8 / 7);
-	octets_written = strlen(decoded);
-	printf("decoded = %s\n\n", osmo_hexdump((uint8_t *)decoded, octets_written));
+	printf("decoded = %s\n\n", osmo_hexdump((uint8_t *)decoded, strlen(decoded)));
 
 	OSMO_ASSERT(strncmp(text, decoded, strlen(text)) == 0);
 	OSMO_ASSERT(strcmp(appended_after_decode, decoded + strlen(text)) == 0);

-- 
To view, visit https://gerrit.osmocom.org/5934
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Ic31805b6a5a917dfc6284edba6ffdd21246ac20c
Gerrit-PatchSet: 2
Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Owner: Vadim Yanitskiy <axilirator at gmail.com>
Gerrit-Reviewer: Harald Welte <laforge at gnumonks.org>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: Vadim Yanitskiy <axilirator at gmail.com>