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laforge gerrit-no-reply at lists.osmocom.orglaforge has uploaded this change for review. ( https://gerrit.osmocom.org/c/libosmocore/+/22121 ) Change subject: tlv_parser: Fix various out-of-bounds accesses ...................................................................... tlv_parser: Fix various out-of-bounds accesses The libosmocore TLV parser had a number of insufficient bounds checks leading to reads beyond the end of the respective input buffer. This patch * adds proper out-of-bounds checks to all TLV types * simplifies some of the existing checks * introduces test cases to test all the corner cases where either TAG, or length, or value are not fully contained in the input buffer. Thanks to Ilja Van Sprundel for reporting these problems. Change-Id: I98b02c914c9e3ecf56050af846292aa6979d7508 --- M src/gsm/tlv_parser.c M tests/tlv/tlv_test.c M tests/tlv/tlv_test.ok 3 files changed, 115 insertions(+), 15 deletions(-) git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/21/22121/1 diff --git a/src/gsm/tlv_parser.c b/src/gsm/tlv_parser.c index 159b42b..5640abe 100644 --- a/src/gsm/tlv_parser.c +++ b/src/gsm/tlv_parser.c @@ -231,7 +231,10 @@ const uint8_t *buf, int buf_len) { uint8_t tag; - int len; + int len; /* number of bytes consumed by TLV entry */ + + if (buf_len < 1) + return -1; tag = *buf; *o_tag = tag; @@ -264,56 +267,54 @@ break; case TLV_TYPE_TLV: tlv: /* GSM TS 04.07 11.2.4: Type 4 TLV */ - if (buf + 1 > buf + buf_len) + if (buf_len < 2) return -1; *o_val = buf+2; *o_len = *(buf+1); len = *o_len + 2; - if (len > buf_len) - return -2; break; case TLV_TYPE_vTvLV_GAN: /* 44.318 / 11.1.4 */ /* FIXME: variable-length TAG! */ + if (buf_len < 2) + return -1; if (*(buf+1) & 0x80) { - /* like TL16Vbut without highest bit of len */ - if (2 > buf_len) + if (buf_len < 3) return -1; + /* like TL16Vbut without highest bit of len */ *o_val = buf+3; *o_len = (*(buf+1) & 0x7F) << 8 | *(buf+2); len = *o_len + 3; - if (len > buf_len) - return -2; } else { /* like TLV */ goto tlv; } break; case TLV_TYPE_TvLV: + if (buf_len < 2) + return -1; if (*(buf+1) & 0x80) { /* like TLV, but without highest bit of len */ - if (buf + 1 > buf + buf_len) - return -1; *o_val = buf+2; *o_len = *(buf+1) & 0x7f; len = *o_len + 2; - if (len > buf_len) - return -2; break; } /* like TL16V, fallthrough */ case TLV_TYPE_TL16V: - if (2 > buf_len) + if (buf_len < 3) return -1; *o_val = buf+3; *o_len = *(buf+1) << 8 | *(buf+2); len = *o_len + 3; - if (len > buf_len) - return -2; break; default: return -3; } + if (buf_len < len) { + *o_val = NULL; + return -2; + } return len; } diff --git a/tests/tlv/tlv_test.c b/tests/tlv/tlv_test.c index 925d762..148a7c2 100644 --- a/tests/tlv/tlv_test.c +++ b/tests/tlv/tlv_test.c @@ -332,6 +332,97 @@ msgb_free(msg); } +static void test_tlv_parser_bounds() +{ + struct tlv_definition tdef; + struct tlv_parsed dec; + uint8_t buf[32]; + + memset(&tdef, 0, sizeof(tdef)); + + printf("Testing TLV_TYPE_T decoder for out-of-bounds\n"); + tdef.def[0x23].type = TLV_TYPE_T; + buf[0] = 0x23; + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 1, 0, 0) == 1); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 0, 0, 0) == 0); + + printf("Testing TLV_TYPE_TV decoder for out-of-bounds\n"); + tdef.def[0x23].type = TLV_TYPE_TV; + buf[0] = 0x23; + buf[1] = 0x42; + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 2, 0, 0) == 1); + OSMO_ASSERT(*TLVP_VAL(&dec, 0x23) == buf[1]); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 1, 0, 0) == -2); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + + printf("Testing TLV_TYPE_FIXED decoder for out-of-bounds\n"); + tdef.def[0x23].type = TLV_TYPE_FIXED; + tdef.def[0x23].fixed_len = 2; + buf[0] = 0x23; + buf[1] = 0x42; + buf[2] = 0x55; + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 3, 0, 0) == 1); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 2, 0, 0) == -2); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + + printf("Testing TLV_TYPE_TLV decoder for out-of-bounds\n"); + tdef.def[0x23].type = TLV_TYPE_TLV; + buf[0] = 0x23; + buf[1] = 0x02; + buf[2] = 0x55; + buf[3] = 0xAA; + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 4, 0, 0) == 1); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == &buf[2]); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 3, 0, 0) == -2); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 2, 0, 0) == -2); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 1, 0, 0) == -1); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + + printf("Testing TLV_TYPE_vTvLV_GAN decoder for out-of-bounds\n"); + tdef.def[0x23].type = TLV_TYPE_vTvLV_GAN; + buf[0] = 0x23; + buf[1] = 0x80; + buf[2] = 0x01; + buf[3] = 0xAA; + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 4, 0, 0) == 1); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == &buf[3]); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 3, 0, 0) == -2); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 2, 0, 0) == -1); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 1, 0, 0) == -1); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + + printf("Testing TLV_TYPE_TvLV decoder for out-of-bounds\n"); + tdef.def[0x23].type = TLV_TYPE_TvLV; + buf[0] = 0x23; + buf[1] = 0x81; + buf[2] = 0xAA; + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 3, 0, 0) == 1); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == &buf[2]); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 2, 0, 0) == -2); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 1, 0, 0) == -1); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + + printf("Testing TLV_TYPE_TL16V decoder for out-of-bounds\n"); + tdef.def[0x23].type = TLV_TYPE_TL16V; + buf[0] = 0x23; + buf[1] = 0x00; + buf[2] = 0x01; + buf[3] = 0xAA; + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 4, 0, 0) == 1); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == &buf[3]); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 3, 0, 0) == -2); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 2, 0, 0) == -1); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); + OSMO_ASSERT(tlv_parse(&dec, &tdef, buf, 1, 0, 0) == -1); + OSMO_ASSERT(TLVP_VAL(&dec, 0x23) == NULL); +} + int main(int argc, char **argv) { //osmo_init_logging2(ctx, &info); @@ -339,6 +430,7 @@ test_tlv_shift_functions(); test_tlv_repeated_ie(); test_tlv_encoder(); + test_tlv_parser_bounds(); printf("Done.\n"); return EXIT_SUCCESS; diff --git a/tests/tlv/tlv_test.ok b/tests/tlv/tlv_test.ok index f3f0fd4..e24b889 100644 --- a/tests/tlv/tlv_test.ok +++ b/tests/tlv/tlv_test.ok @@ -1,4 +1,11 @@ Test shift functions Testing TLV encoder by decoding + re-encoding binary Testing TLV encoder with IE ordering +Testing TLV_TYPE_T decoder for out-of-bounds +Testing TLV_TYPE_TV decoder for out-of-bounds +Testing TLV_TYPE_FIXED decoder for out-of-bounds +Testing TLV_TYPE_TLV decoder for out-of-bounds +Testing TLV_TYPE_vTvLV_GAN decoder for out-of-bounds +Testing TLV_TYPE_TvLV decoder for out-of-bounds +Testing TLV_TYPE_TL16V decoder for out-of-bounds Done. -- To view, visit https://gerrit.osmocom.org/c/libosmocore/+/22121 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: libosmocore Gerrit-Branch: for-1.4 Gerrit-Change-Id: I98b02c914c9e3ecf56050af846292aa6979d7508 Gerrit-Change-Number: 22121 Gerrit-PatchSet: 1 Gerrit-Owner: laforge <laforge at osmocom.org> Gerrit-MessageType: newchange -------------- next part -------------- An HTML attachment was scrubbed... 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