High level conclusions

Fuzzers reach 14.96% of cyclomatic complexity.

Fuzzers reach 18.58% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

97 / 522

Cyclomatic complexity statically reachable by fuzzers

470 / 3141

Runtime code coverage of functions

72 / 522

The following table shows data about each function in the project. The functions included in this table correspond to all functions that exist in the executables of the fuzzers. As such, there may be functions that are from third-party libraries.

For further technical details on the meaning of columns in the below table, please see the Glossary .

Func name	Functions filename	Args	Function call depth	Reached by Fuzzers	Runtime reached by Fuzzers	Combined reached by Fuzzers	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

Fuzzer: /src/tinyusb/test/fuzz/device/msc/src/fuzz.cc

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	57	58.7%
gold	[1:9]	20	20.6%
yellow	[10:29]	7	7.21%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	13	13.4%
All colors	97	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
40	45	status_stage_xact	call site: 00045	process_get_descriptor
6	34	process_control_request	call site: 00034	tud_control_xfer
2	14	tu_fifo_write	call site: 00014	tud_event_hook_cb
2	27	usbd_reset	call site: 00027	usbd_reset
2	94	tud_task_ext	call site: 00094	tud_resume_cb
1	10	dcd_int_handler	call site: 00010	tu_fifo_write
1	24	tu_fifo_read	call site: 00024	usbd_reset
1	43	usbd_edpt_xfer	call site: 00043	status_stage_xact
1	87	tud_task_ext	call site: 00087	usbd_control_xfer_cb
1	92	usbd_control_xfer_cb	call site: 00092	data_stage_xact

Runtime coverage analysis

Covered functions

101

Functions that are reachable but not covered

23

Reachable functions

59

Percentage of reachable functions covered

61.02%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc	1
/src/tinyusb/test/fuzz/fuzz.cc	1
/src/tinyusb/src/device/usbd.c	21
/src/tinyusb/src/common/tusb_fifo.c	8
/src/tinyusb/test/fuzz/dcd_fuzz.cc	9
/src/tinyusb/src/device/usbd_control.c	9
/src/tinyusb/test/fuzz/usbd_fuzz.cc	4
/src/tinyusb/test/fuzz/device/msc/src/usb_descriptors.cc	3
/src/tinyusb/src/tusb.c	1

Fuzzer: /src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	78	49.3%
gold	[1:9]	20	12.6%
yellow	[10:29]	19	12.0%
greenyellow	[30:49]	6	3.79%
lawngreen	50+	35	22.1%
All colors	158	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
40	45	status_stage_xact	call site: 00045	process_get_descriptor
6	34	process_control_request	call site: 00034	tud_control_xfer
6	149	cdc_task	call site: 00149	tud_cdc_n_write_flush
3	94	tud_task_ext	call site: 00094	cdc_task
3	114	tu_edpt_stream_read	call site: 00114	usbd_edpt_xfer
3	121	tu_edpt_stream_read_xfer	call site: 00121	tud_cdc_n_read
2	14	tu_fifo_write	call site: 00014	tud_event_hook_cb
2	27	usbd_reset	call site: 00027	usbd_reset
2	104	cdc_task	call site: 00104	tud_cdc_n_available
2	132	tud_cdc_n_write	call site: 00132	usbd_edpt_xfer
1	10	dcd_int_handler	call site: 00010	tu_fifo_write
1	18	dcd_int_handler	call site: 00018	tud_task_ext

Runtime coverage analysis

Covered functions

101

Functions that are reachable but not covered

30

Reachable functions

94

Percentage of reachable functions covered

68.09%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc	2
/src/tinyusb/test/fuzz/fuzz.cc	1
/src/tinyusb/src/device/usbd.c	26
/src/tinyusb/src/common/tusb_fifo.c	18
/src/tinyusb/test/fuzz/dcd_fuzz.cc	9
/src/tinyusb/src/device/usbd_control.c	9
/src/tinyusb/test/fuzz/usbd_fuzz.cc	4
/src/tinyusb/test/fuzz/device/cdc/src/usb_descriptors.cc	3
/src/tinyusb/src/tusb.c	8
/src/tinyusb/src/class/cdc/cdc_device.c	12

Fuzzer: /src/tinyusb/test/fuzz/device/net/src/fuzz.cc

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	69	64.4%
gold	[1:9]	19	17.7%
yellow	[10:29]	7	6.54%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	12	11.2%
All colors	107	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
40	45	status_stage_xact	call site: 00045	process_get_descriptor
12	94	tud_task_ext	call site: 00094	net_task
6	34	process_control_request	call site: 00034	tud_control_xfer
2	14	tu_fifo_write	call site: 00014	tud_event_hook_cb
2	27	usbd_reset	call site: 00027	usbd_reset
1	7	tud_rhport_init	call site: 00007	dcd_int_handler
1	10	dcd_int_handler	call site: 00010	tu_fifo_write
1	18	dcd_int_handler	call site: 00018	tud_task_ext
1	24	tu_fifo_read	call site: 00024	usbd_reset
1	43	usbd_edpt_xfer	call site: 00043	status_stage_xact
1	87	tud_task_ext	call site: 00087	usbd_control_xfer_cb
1	92	usbd_control_xfer_cb	call site: 00092	data_stage_xact

Runtime coverage analysis

Covered functions

101

Functions that are reachable but not covered

29

Reachable functions

65

Percentage of reachable functions covered

55.38%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/src/tinyusb/test/fuzz/device/net/src/fuzz.cc	2
/src/tinyusb/test/fuzz/fuzz.cc	1
/src/tinyusb/src/device/usbd.c	21
/src/tinyusb/src/common/tusb_fifo.c	8
/src/tinyusb/test/fuzz/dcd_fuzz.cc	9
/src/tinyusb/src/device/usbd_control.c	9
/src/tinyusb/test/fuzz/usbd_fuzz.cc	4
/src/tinyusb/test/fuzz/device/net/src/usb_descriptors.cc	3
/src/tinyusb/src/tusb.c	1
/src/tinyusb/src/class/net/ecm_rndis_device.c	4
/src/tinyusb/test/fuzz/net_fuzz.cc	1

Optimal target analysis

Remaining optimal interesting functions

The following table shows a list of functions that are optimal targets. Optimal targets are identified by finding the functions that in combination, yield a high code coverage.

Func name	Functions filename	Arg count	Args	Function depth	hitcount	instr count	bb count	cyclomatic complexity	Reachable functions	Incoming references	total cyclomatic complexity	Unreached complexity
netif_input	/src/tinyusb/lib/lwip/src/core/netif.c	2	['N/A', 'N/A']	11	0	28	6	3	133	0	1138	1138
httpd_init_pcb	/src/tinyusb/lib/lwip/src/apps/http/httpd.c	1	['N/A']	22	0	25	6	3	125	1	781	258
mscd_xfer_cb	/src/tinyusb/src/class/msc/msc_device.c	4	['char', 'char', 'int', 'int']	6	0	387	92	34	37	0	233	168
netd_control_xfer_cb	/src/tinyusb/src/class/net/ecm_rndis_device.c	3	['char', 'char', 'N/A']	7	0	266	63	24	21	0	161	118
dhserv_init	/src/tinyusb/lib/networking/dhserver.c	1	['N/A']	9	0	40	8	4	49	0	272	95
netif_add_noaddr	/src/tinyusb/lib/lwip/src/core/netif.c	4	['N/A', 'N/A', 'N/A', 'N/A']	18	0	12	3	2	68	0	363	60
etharp_output	/src/tinyusb/lib/lwip/src/core/ipv4/etharp.c	3	['N/A', 'N/A', 'N/A']	9	0	161	29	12	32	0	208	41
cdcd_xfer_cb	/src/tinyusb/src/class/cdc/cdc_device.c	4	['char', 'char', 'int', 'int']	5	0	234	54	21	23	0	129	38

Implementing fuzzers that target the above functions will improve reachability such that it becomes:

Functions statically reachable by fuzzers

344 / 522

Cyclomatic complexity statically reachable by fuzzers

2376 / 3141

All functions overview

If you implement fuzzers for these functions, the status of all functions in the project will be:

Func name	Functions filename	Args	Function call depth	Reached by Fuzzers	Runtime reached by Fuzzers	Combined reached by Fuzzers	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

This sections provides heuristics that can be used as input to a fuzz engine when running a given fuzz target. The current focus is on providing input that is usable by libFuzzer.

/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['status_stage_xact', 'process_control_request', 'tu_fifo_write', 'usbd_reset', 'tud_task_ext', 'dcd_int_handler', 'tu_fifo_read', 'usbd_edpt_xfer', 'usbd_control_xfer_cb']

/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['status_stage_xact', 'process_control_request', 'cdc_task', 'tud_task_ext', 'tu_edpt_stream_read', 'tu_edpt_stream_read_xfer', 'tu_fifo_write', 'usbd_reset', 'tud_cdc_n_write']

/src/tinyusb/test/fuzz/device/net/src/fuzz.cc

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['status_stage_xact', 'tud_task_ext', 'process_control_request', 'tu_fifo_write', 'usbd_reset', 'tud_rhport_init', 'dcd_int_handler', 'tu_fifo_read', 'usbd_edpt_xfer']

This section shows analysis of runtime coverage data.

For futher technical details on how this section is generated, please see the Glossary .

Complex functions with low coverage

Func name	Function total lines	Lines covered at runtime	percentage covered	Reached by fuzzers
cdcd_xfer_cb	31	5	16.12%	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc']
tud_task_ext	91	34	37.36%	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc']
dcd_event_handler	70	18	25.71%	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc']
process_control_request	152	7	4.605%	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc']

This section shows which files and directories are considered in this report. The main reason for showing this is fuzz introspector may include more code in the reasoning than is desired. This section helps identify if too many files/directories are included, e.g. third party code, which may be irrelevant for the threat model. In the event too much is included, fuzz introspector supports a configuration file that can exclude data from the report. See the following link for more information on how to create a config file: link

Files in report

Source file	Reached by	Covered by
	[]	[]
/src/tinyusb/test/fuzz/device/msc/src/usb_descriptors.cc	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc']	[]
/usr/local/bin/../include/c++/v1/stdexcept	[]	[]
/src/tinyusb/lib/lwip/src/core/memp.c	[]	[]
/src/tinyusb/lib/lwip/src/core/timeouts.c	[]	[]
/src/tinyusb/lib/lwip/src/core/ipv4/icmp.c	[]	[]
/src/tinyusb/lib/lwip/src/core/netif.c	[]	[]
/src/tinyusb/lib/lwip/src/core/tcp.c	[]	[]
/src/tinyusb/lib/lwip/src/core/tcp_in.c	[]	[]
/src/tinyusb/lib/networking/dnserver.c	[]	[]
/src/tinyusb/lib/lwip/src/core/ipv4/etharp.c	[]	[]
/src/tinyusb/lib/lwip/src/apps/http/httpd.c	[]	[]
/src/tinyusb/src/device/usbd.c	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']
/src/tinyusb/lib/lwip/src/core/ipv4/ip4_addr.c	[]	[]
/src/tinyusb/lib/lwip/src/core/stats.c	[]	[]
/src/tinyusb/lib/networking/rndis_reports.c	[]	[]
/src/tinyusb/lib/lwip/src/apps/http/fs.c	[]	[]
/src/tinyusb/test/fuzz/fuzz.cc	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']
/src/tinyusb/lib/lwip/src/core/ipv4/ip4_frag.c	[]	[]
/src/tinyusb/lib/lwip/src/core/udp.c	[]	[]
/src/tinyusb/src/tusb.c	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']
/src/tinyusb/lib/lwip/src/core/def.c	[]	[]
/src/tinyusb/lib/networking/dhserver.c	[]	[]
/src/tinyusb/test/fuzz/usbd_fuzz.cc	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']
/src/tinyusb/lib/lwip/src/core/mem.c	[]	[]
/src/tinyusb/test/fuzz/device/net/src/usb_descriptors.cc	['/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	[]
/src/tinyusb/test/fuzz/msc_fuzz.cc	[]	[]
/src/tinyusb/src/class/cdc/cdc_device.c	['/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc']
/src/tinyusb/test/fuzz/net_fuzz.cc	['/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	[]
/src/tinyusb/lib/lwip/src/core/init.c	[]	[]
/src/tinyusb/lib/lwip/src/netif/slipif.c	[]	[]
/src/tinyusb/lib/lwip/src/core/ipv4/ip4.c	[]	[]
/src/tinyusb/src/common/tusb_fifo.c	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']
/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc']
/usr/local/bin/../include/c++/v1/optional	[]	[]
/src/tinyusb/test/fuzz/device/cdc/src/usb_descriptors.cc	['/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc']	[]
/src/tinyusb/src/class/msc/msc_device.c	[]	[]
/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc	['/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc']
/src/tinyusb/test/fuzz/dcd_fuzz.cc	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']
/src/tinyusb/lib/lwip/src/core/tcp_out.c	[]	[]
/src/tinyusb/src/device/usbd_control.c	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/msc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/cdc/src/fuzz.cc', '/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']
/src/tinyusb/lib/lwip/src/netif/ethernet.c	[]	[]
/src/tinyusb/src/class/net/ecm_rndis_device.c	['/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	[]
/src/tinyusb/lib/lwip/src/core/pbuf.c	[]	[]
/src/tinyusb/test/fuzz/device/net/src/fuzz.cc	['/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']	['/src/tinyusb/test/fuzz/device/net/src/fuzz.cc']
/src/tinyusb/lib/lwip/src/core/inet_chksum.c	[]	[]

Directories in report

Directory
/src/tinyusb/src/
/src/tinyusb/src/device/
/src/tinyusb/src/class/cdc/
/src/tinyusb/lib/lwip/src/apps/http/
/src/tinyusb/src/class/msc/
/src/tinyusb/test/fuzz/
/src/tinyusb/test/fuzz/device/cdc/src/
/src/tinyusb/src/class/net/
/src/tinyusb/lib/lwip/src/netif/
/usr/local/bin/../include/c++/v1/
/src/tinyusb/lib/networking/
/src/tinyusb/lib/lwip/src/core/
/src/tinyusb/test/fuzz/device/msc/src/
/src/tinyusb/test/fuzz/device/net/src/
/src/tinyusb/src/common/
/src/tinyusb/lib/lwip/src/core/ipv4/