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authorHarald Welte <laforge@gnumonks.org>2019-01-20 10:37:49 +0100
committerHarald Welte <laforge@gnumonks.org>2019-01-22 14:53:46 +0000
commit1c3bae138cea1dbde480ce4382120034eb769e82 (patch)
treefc297ba07badb2ae23fa0a93e00457c50b64209b
parent1317771c9340a9fdc86911206cdc8719a3d2bfe6 (diff)
constrain gsm48_generate_mid() output array bounds
The longest BCd-digit type identity is the IMEISV with 16, so there's no point in trying to parse up to 255 decimal digits, which will do nothing but to overflow the caller-provided output buffer. Let's also clearly define the required minimum size of the output buffer and add a reltead #define for it. Change-Id: Ic8488bc7f77dc9182e372741b88f0f06100dddc9
-rw-r--r--include/osmocom/gsm/gsm48.h1
-rw-r--r--src/gb/gprs_bssgp.c4
-rw-r--r--src/gb/gprs_bssgp_bss.c2
-rw-r--r--src/gsm/gsm48.c12
4 files changed, 12 insertions, 7 deletions
diff --git a/include/osmocom/gsm/gsm48.h b/include/osmocom/gsm/gsm48.h
index 0f5727a..7e0e5c4 100644
--- a/include/osmocom/gsm/gsm48.h
+++ b/include/osmocom/gsm/gsm48.h
@@ -45,6 +45,7 @@ void gsm48_generate_lai(struct gsm48_loc_area_id *lai48, uint16_t mcc,
OSMO_DEPRECATED("Use gsm48_generate_lai2() instead, to not lose leading zeros in the MNC");
void gsm48_generate_lai2(struct gsm48_loc_area_id *lai48, const struct osmo_location_area_id *lai);
+#define GSM48_MID_MAX_SIZE 11
int gsm48_generate_mid_from_tmsi(uint8_t *buf, uint32_t tmsi);
int gsm48_generate_mid_from_imsi(uint8_t *buf, const char *imsi);
uint8_t gsm48_generate_mid(uint8_t *buf, const char *id, uint8_t mi_type);
diff --git a/src/gb/gprs_bssgp.c b/src/gb/gprs_bssgp.c
index 3b9fbf9..be7ef9f 100644
--- a/src/gb/gprs_bssgp.c
+++ b/src/gb/gprs_bssgp.c
@@ -1156,7 +1156,7 @@ int bssgp_tx_dl_ud(struct msgb *msg, uint16_t pdu_lifetime,
/* IMSI */
if (dup->imsi && strlen(dup->imsi)) {
- uint8_t mi[10];
+ uint8_t mi[GSM48_MID_MAX_SIZE];
int imsi_len = gsm48_generate_mid_from_imsi(mi, dup->imsi);
if (imsi_len > 2)
msgb_tvlv_push(msg, BSSGP_IE_IMSI,
@@ -1205,7 +1205,7 @@ int bssgp_tx_paging(uint16_t nsei, uint16_t ns_bvci,
struct bssgp_normal_hdr *bgph =
(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));
uint16_t drx_params = osmo_htons(pinfo->drx_params);
- uint8_t mi[10];
+ uint8_t mi[GSM48_MID_MAX_SIZE];
int imsi_len = gsm48_generate_mid_from_imsi(mi, pinfo->imsi);
struct gsm48_ra_id ra;
diff --git a/src/gb/gprs_bssgp_bss.c b/src/gb/gprs_bssgp_bss.c
index 487286c..77350e2 100644
--- a/src/gb/gprs_bssgp_bss.c
+++ b/src/gb/gprs_bssgp_bss.c
@@ -178,7 +178,7 @@ int bssgp_tx_radio_status_imsi(struct bssgp_bvc_ctx *bctx, uint8_t cause,
const char *imsi)
{
struct msgb *msg = common_tx_radio_status(bctx);
- uint8_t mi[10];
+ uint8_t mi[GSM48_MID_MAX_SIZE];
int imsi_len = gsm48_generate_mid_from_imsi(mi, imsi);
if (!msg)
diff --git a/src/gsm/gsm48.c b/src/gsm/gsm48.c
index 795e98b..86d40d4 100644
--- a/src/gsm/gsm48.c
+++ b/src/gsm/gsm48.c
@@ -637,20 +637,23 @@ int gsm48_generate_mid_from_tmsi(uint8_t *buf, uint32_t tmsi)
return 7;
}
-/*! Generate TS 24.008 §10.5.1.4 Mobile ID
- * \param[out] buf Caller-provided output buffer
+/*! Generate TS 24.008 §10.5.1.4 Mobile ID of BCD type from ASCII string
+ * \param[out] buf Caller-provided output buffer of at least GSM48_MID_MAX_SIZE bytes
* \param[in] id Identity to be encoded
- * \param[in] mi_type Type of identity (e.g. GSM_MI_TYPE_TMSI)
+ * \param[in] mi_type Type of identity (e.g. GSM_MI_TYPE_IMSI, IMEI, IMEISV)
* \returns number of bytes used in \a buf */
uint8_t gsm48_generate_mid(uint8_t *buf, const char *id, uint8_t mi_type)
{
- uint8_t length = strnlen(id, 255), i, off = 0, odd = (length & 1) == 1;
+ uint8_t length = strnlen(id, 16), i, off = 0, odd = (length & 1) == 1;
+ /* maximum length == 16 (IMEISV) */
buf[0] = GSM48_IE_MOBILE_ID;
buf[2] = osmo_char2bcd(id[0]) << 4 | (mi_type & GSM_MI_TYPE_MASK) | (odd << 3);
/* if the length is even we will fill half of the last octet */
buf[1] = (length + (odd ? 1 : 2)) >> 1;
+ /* buf[1] maximum = 18/2 = 9 */
+ OSMO_ASSERT(buf[1] <= 9);
for (i = 1; i < buf[1]; ++i) {
uint8_t upper, lower = osmo_char2bcd(id[++off]);
@@ -662,6 +665,7 @@ uint8_t gsm48_generate_mid(uint8_t *buf, const char *id, uint8_t mi_type)
buf[2 + i] = (upper << 4) | lower;
}
+ /* maximum return value: 2 + 9 = 11 */
return 2 + buf[1];
}