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ORAN: Fix possible divide by zero errors 

Report as expert info errors and bail on BFW extension
header if see invalid values (that would have resulted
in division by 0).
This commit is contained in:
Martin Mathieson 2020-12-12 22:37:54 +00:00 committed by AndersBroman
parent e92119c608
commit 1a3703cc3e
1 changed files with 55 additions and 16 deletions
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71
epan/dissectors/packet-oran.c
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@ -93,6 +93,7 @@ static int hf_oran_reserved = -1;
/* static int hf_oran_bfwCompParam = -1; */
static int hf_oran_bfwCompHdr_iqWidth = -1;
static int hf_oran_bfwCompHdr_compMeth = -1;
static int hf_oran_num_bf_weights = -1;
static int hf_oran_symbolId = -1;
static int hf_oran_startPrbu = -1;
static int hf_oran_numPrbu = -1;
@ -124,6 +125,10 @@ static gint ett_oran_iq = -1;
static gint ett_oran_c_section_extension = -1;
static gint ett_oran_bfw = -1;
/* Expert info */
static expert_field ei_oran_invalid_bfw_iqwidth = EI_INIT;
static expert_field ei_oran_invalid_num_bfw_weights = EI_INIT;
static guint sample_bit_width_uplink = 14;
static guint sample_bit_width_downlink = 14;
@ -524,7 +529,8 @@ static int dissect_oran_c_section(tvbuff_t *tvb, proto_tree *tree, packet_info *
{
/* bfwCompHdr (2 subheaders - bfwIqWidth and bfwCompMeth)*/
guint32 bfwcomphdr_iq_width, bfwcomphdr_comp_meth;
proto_tree_add_item_ret_uint(extension_tree, hf_oran_bfwCompHdr_iqWidth, tvb, offset, 1, ENC_BIG_ENDIAN, &bfwcomphdr_iq_width);
proto_item *iqwidth_ti = proto_tree_add_item_ret_uint(extension_tree, hf_oran_bfwCompHdr_iqWidth,
tvb, offset, 1, ENC_BIG_ENDIAN, &bfwcomphdr_iq_width);
proto_tree_add_item_ret_uint(extension_tree, hf_oran_bfwCompHdr_compMeth, tvb, offset, 1, ENC_BIG_ENDIAN, &bfwcomphdr_comp_meth);
offset++;
@ -541,10 +547,27 @@ static int dissect_oran_c_section(tvbuff_t *tvb, proto_tree *tree, packet_info *
iq_width = 15;
break;
default:
/* TODO: error!!!!! */
/* Error! */
break;
}
/* Show num_bf_weights as a generated field */
proto_item *num_bf_weights_ti = proto_tree_add_uint(extension_tree, hf_oran_num_bf_weights, tvb, 0, 0, num_bf_weights);
proto_item_set_generated(num_bf_weights_ti);
/* Must have valid values for these two... */
if (iq_width == 0) {
expert_add_info_format(pinfo, iqwidth_ti, &ei_oran_invalid_bfw_iqwidth,
"BFW IQ Width (%u) not valid", bfwcomphdr_iq_width);
break;
}
if (num_bf_weights == 0) {
expert_add_info_format(pinfo, num_bf_weights_ti, &ei_oran_invalid_num_bfw_weights,
"Number of BF weights (from preference) must not be 0!");
break;
}
/* bfwCompParam */
switch (bfwcomphdr_comp_meth) {
case 0: /* no compression */
@ -567,7 +590,7 @@ static int dissect_oran_c_section(tvbuff_t *tvb, proto_tree *tree, packet_info *
*/
/* I & Q samples
TODO: don't know how many there will be, so just fill available bytes...
Don't know how many there will be, so just fill available bytes...
*/
guint weights_bytes = (extlen*4)-3;
guint num_weights_pairs = (weights_bytes*8) / (iq_width*2);
@ -944,8 +967,7 @@ proto_register_oran(void)
{ "E Bit", "oran_fh_cus.e_bit",
FT_UINT8, BASE_DEC,
VALS(e_bit), 0x80,
"One bit (the \"E-bit\") is reserved to indi"
"cate the last message of a subsequence.",
"One bit (the \"E-bit\") is reserved to indicate the last message of a subsequence.",
HFILL }
},
@ -1002,8 +1024,7 @@ proto_register_oran(void)
{"Frame ID", "oran_fh_cus.frameId",
FT_UINT8, BASE_DEC,
NULL, 0x00,
"This parameter is a counter for 10 ms frames (wrapping period 2."
"56 seconds)",
"This parameter is a counter for 10 ms frames (wrapping period 2.56 seconds)",
HFILL}},
/* Section 5.4.4.5 */
@ -1079,7 +1100,7 @@ proto_register_oran(void)
NULL, 0x0,
"This parameter defines the time_offset from the start of the slot "
"to the start of the Cyclic Prefix (CP) in number of samples tsample "
"(=1/30.72MHz as specified in 3GPP TS38.211 section 4.1). "
"(=1/30.72MHz as specified in 3GPP TS38.211 section 4.1). "
"Because this is denominated in \"samples\" there is no fixed "
"microsecond unit for this parameter; time_offset = \"n\" may be longer "
"or shorter in time depending on the sampling interval (which is "
@ -1164,7 +1185,7 @@ proto_register_oran(void)
"the message as long as symInc is zero. When symInc is one, the "
"maintained symbol number should be incremented by one, and that "
"new symbol number should be used for that section and each subsequent "
"section until the symInc bit is again detected to be one. "
"section until the symInc bit is again detected to be one. "
"In this manner, multiple symbols may be handled by a single C-Plane "
"message.",
HFILL}},
@ -1378,10 +1399,10 @@ proto_register_oran(void)
{"Backoff Counter", "oran_fh_cus.lbtBackoffCounter",
FT_UINT16, BASE_DEC,
NULL, 0x03ff,
"LBT backoff counter in sensing slots as described in 3GPP TS 36."
"213 Section 15.1.1. This parameter is used for LBT CAT 4 and can "
"take one of nine values: {3, 7, 15, 31, 63, 127, 255, 511, 1023"
"} based on the priority class. Four priority classes are defined "
"LBT backoff counter in sensing slots as described in 3GPP TS 36.213 "
"Section 15.1.1. This parameter is used for LBT CAT 4 and can "
"take one of nine values: {3, 7, 15, 31, 63, 127, 255, 511, 1023} "
"based on the priority class. Four priority classes are defined "
"in 3GPP TS 36.213.",
HFILL}},
@ -1496,6 +1517,14 @@ proto_register_oran(void)
"not some subset of them.",
HFILL}},
{&hf_oran_num_bf_weights,
{"Number of BF weights", "oran_fh_cus.num_bf_weights",
FT_UINT16, BASE_DEC,
NULL, 0x0,
"This is the number of BF weights per antenna - currently set in a preference",
HFILL}},
#if 0
/* FIXME Section 5.4.7.1.2 */
{ &hf_oran_bfwCompParam.
@ -1602,8 +1631,8 @@ proto_register_oran(void)
{ "Exponent", "oran_fh_cus.exponent",
FT_UINT8, BASE_DEC,
NULL, 0x0f,
"This parameter exponent applicable to the I & Q mantissas."
"NOTE : Exponent is used for all mantissa sample sizes(i.e. 6bit"
"This parameter exponent applicable to the I & Q mantissas. "
"NOTE : Exponent is used for all mantissa sample sizes(i.e. 6bit "
"- 16bit). Likewise, a native \"uncompressed\" format is not supported "
"within this specification.",
HFILL } },
@ -1613,7 +1642,7 @@ proto_register_oran(void)
FT_BYTES, BASE_NONE,
NULL, 0x0,
"This parameter is used for the In-phase and Quadrature sample "
"mantissa. Twelve I/Q Samples are included per resource block. The width"
"mantissa. Twelve I/Q Samples are included per resource block. The width "
"of the mantissa can be between 6 and 16 bits",
HFILL } },
@ -1650,6 +1679,13 @@ proto_register_oran(void)
&ett_oran_bfw
};
expert_module_t* expert_oran;
static ei_register_info ei[] = {
{ &ei_oran_invalid_bfw_iqwidth, { "oran_fh_cus.bfw_iqwidth_invalid", PI_MALFORMED, PI_ERROR, "Invalid IQ Width", EXPFILL }},
{ &ei_oran_invalid_num_bfw_weights, { "oran_fh_cus.num_bf_weights_invalid", PI_MALFORMED, PI_ERROR, "Invalid number of BF Weights", EXPFILL }}
};
/* Register the protocol name and description */
proto_oran = proto_register_protocol("O-RAN Fronthaul CUS", "O-RAN FH CUS", "oran_fh_cus");
@ -1660,6 +1696,9 @@ proto_register_oran(void)
proto_register_field_array(proto_oran, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_oran = expert_register_protocol(proto_oran);
expert_register_field_array(expert_oran, ei, array_length(ei));
module_t * oran_module = prefs_register_protocol(proto_oran, NULL);
/* Register bit width/compression preferences separately by direction. */