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Add bounds checks for truncated DLF packet parsing #147

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10 changes: 10 additions & 0 deletions src/scat/parsers/qualcomm/diagltelogparser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -690,10 +690,14 @@ def parse_lte_mac_subpkt_v1_ul_transport_block(self, pkt_header, subpkt_hdr, sub
subpkt_pos = 1
for j in range(n_samples):
if subpkt_hdr.version == 0x01:
if subpkt_pos + 12 > len(subpkt_body):
break
subpkt_mac_ul_tb = subpkt_mac_ul_tb_struct._make(struct.unpack('<BBHHBHBBB', subpkt_body[subpkt_pos:subpkt_pos+12]))
mac_hdr = subpkt_body[subpkt_pos+12:subpkt_pos+12+subpkt_mac_ul_tb.header_len]
subpkt_pos += (12 + subpkt_mac_ul_tb.header_len)
elif subpkt_hdr.version == 0x02 or subpkt_hdr.version == 0x03 or subpkt_hdr.version == 0x05 or subpkt_hdr.version == 0x08:
if subpkt_pos + 14 > len(subpkt_body):
break
subpkt_mac_ul_tb = subpkt_mac_ul_tb_struct_v2._make(struct.unpack('<BBBBHHBHBBB', subpkt_body[subpkt_pos:subpkt_pos+14]))
mac_hdr = subpkt_body[subpkt_pos+14:subpkt_pos+14+subpkt_mac_ul_tb.header_len]
subpkt_pos += (14 + subpkt_mac_ul_tb.header_len)
Expand Down Expand Up @@ -759,6 +763,8 @@ def parse_lte_mac_subpkt_v49(self, pkt_header, pkt_body: bytes, args: dict, is_d
if pkt_version == 0x31:
pos += (19 * 28)
for i in range(num_tb):
if pos + 16 > len(pkt_body):
break
subpkt_tb = subpkt_tb_common_info._make(struct.unpack('<LLL B B H', pkt_body[pos:pos+16]))
pos += 16

Expand All @@ -774,6 +780,8 @@ def parse_lte_mac_subpkt_v49(self, pkt_header, pkt_body: bytes, args: dict, is_d
mac_hdr_len = var3_bits[0:12].uint

for j in range(subpkt_tb.num_sdu):
if pos + 3 > len(pkt_body):
break
mac_common_info_bits = bitstring.Bits(pkt_body[pos:pos+3][::-1])
is_mce = mac_common_info_bits[0:1].uint
lcid = mac_common_info_bits[1:7].uint
Expand Down Expand Up @@ -831,6 +839,8 @@ def parse_lte_mac_subpkt_v49(self, pkt_header, pkt_body: bytes, args: dict, is_d
for k in range(num_pdcp_grp):
has_more = 1
while has_more == 1:
if pos + 4 > len(pkt_body):
break
pdcp_grp_bits = bitstring.Bits(pkt_body[pos:pos+4][::-1])
has_more = pdcp_grp_bits[0:1].uint
pos += 4
Expand Down
3 changes: 3 additions & 0 deletions src/scat/writers/pcapwriter.py
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Expand Up @@ -29,6 +29,9 @@ def __enter__(self):
return self

def write_pkt(self, sock_content: bytes, port: int, radio_id: int=0, ts: datetime.datetime = datetime.datetime.now()) -> None:
max_payload = 65535 - 8 - 20 # max UDP payload fitting in IPv4
if len(sock_content) > max_payload:
return
pcap_hdr = struct.pack('<LLLL',
int(ts.timestamp()) % 4294967296,
ts.microsecond,
Expand Down