High level conclusions

Fuzzers reach 15.0% of cyclomatic complexity.

Fuzzers reach 18.33% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

95 / 518

Cyclomatic complexity statically reachable by fuzzers

468 / 3120

Runtime code coverage of functions

60 / 518

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/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	92	61.7%
gold	[1:9]	17	11.4%
yellow	[10:29]	3	2.01%
greenyellow	[30:49]	7	4.69%
lawngreen	50+	30	20.1%
All colors	149	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
54	42	usbd_edpt_xfer	call site: 00042	cdc_task
13	28	tud_task_ext	call site: 00028	process_control_request
9	113	tu_edpt_stream_read_xfer	call site: 00113	tud_cdc_n_read
4	142	cdc_task	call site: 00142	tud_cdc_n_write_flush
3	136	tu_edpt_stream_write_xfer	call site: 00136	stream_xfer
2	13	tu_fifo_write	call site: 00013	tud_event_hook_cb
2	108	tu_fifo_read_n_access_mode	call site: 00108	ff_pull_n
1	8	tud_rhport_init	call site: 00008	dcd_int_handler
1	11	dcd_int_handler	call site: 00011	tu_fifo_write
1	17	dcd_int_handler	call site: 00017	tud_task_ext
1	21	tu_fifo_read	call site: 00021	correct_read_index
1	100	tud_cdc_n_connected	call site: 00100	tud_cdc_n_get_line_state

Runtime coverage analysis

Covered functions

90

Functions that are reachable but not covered

47

Reachable functions

92

Percentage of reachable functions covered

48.91%

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.

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/tusb.c	12
/src/tinyusb/src/device/usbd.c	26
/src/tinyusb/src/common/tusb_fifo.c	12
/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/class/cdc/cdc_device.c	12

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	70	72.9%
gold	[1:9]	11	11.4%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	15	15.6%
All colors	96	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
53	42	usbd_edpt_xfer	call site: 00042	process_get_descriptor
13	28	tud_task_ext	call site: 00028	process_control_request
2	13	tu_fifo_write	call site: 00013	tud_event_hook_cb
1	11	dcd_int_handler	call site: 00011	tu_fifo_write
1	21	tu_fifo_read	call site: 00021	correct_read_index

Runtime coverage analysis

Covered functions

90

Functions that are reachable but not covered

35

Reachable functions

58

Percentage of reachable functions covered

39.66%

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/tusb.c	2
/src/tinyusb/src/device/usbd.c	21
/src/tinyusb/src/common/tusb_fifo.c	6
/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

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	78	73.5%
gold	[1:9]	11	10.3%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	17	16.0%
All colors	106	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
54	42	usbd_edpt_xfer	call site: 00042	process_get_descriptor
13	28	tud_task_ext	call site: 00028	process_control_request
4	101	net_task	call site: 00101	do_in_xfer
2	13	tu_fifo_write	call site: 00013	tud_event_hook_cb
1	0	EP	call site: 00000	fuzz_init
1	8	tud_rhport_init	call site: 00008	dcd_int_handler
1	11	dcd_int_handler	call site: 00011	tu_fifo_write
1	17	dcd_int_handler	call site: 00017	tud_task_ext
1	21	tu_fifo_read	call site: 00021	correct_read_index

Runtime coverage analysis

Covered functions

90

Functions that are reachable but not covered

37

Reachable functions

64

Percentage of reachable functions covered

42.19%

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/tusb.c	2
/src/tinyusb/src/device/usbd.c	21
/src/tinyusb/src/common/tusb_fifo.c	6
/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/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	35	0	230	168
netd_control_xfer_cb	/src/tinyusb/src/class/net/ecm_rndis_device.c	3	['char', 'char', 'N/A']	7	0	266	63	24	20	0	151	108
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
cdcd_xfer_cb	/src/tinyusb/src/class/cdc/cdc_device.c	4	['char', 'char', 'int', 'int']	4	0	282	64	25	25	0	142	48
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

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

Functions statically reachable by fuzzers

342 / 518

Cyclomatic complexity statically reachable by fuzzers

2374 / 3120

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/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=['usbd_edpt_xfer', 'tud_task_ext', 'tu_edpt_stream_read_xfer', 'cdc_task', 'tu_edpt_stream_write_xfer', 'tu_fifo_write', 'tu_fifo_read_n_access_mode', 'tud_rhport_init', 'dcd_int_handler']

/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=['usbd_edpt_xfer', 'tud_task_ext', 'tu_fifo_write', 'dcd_int_handler', 'tu_fifo_read']

/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=['usbd_edpt_xfer', 'tud_task_ext', 'net_task', 'tu_fifo_write', 'tud_rhport_init', 'dcd_int_handler', 'tu_fifo_read']

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
tud_task_ext	91	39	42.85%	['/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']
mscd_xfer_cb	131	11	8.396%	['/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']

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

Directories in report

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