Segfault when tried to access request->map_post_body

[NakedSolidSnake]

Describe the issue
I'm getting a segfault when I'm trying to get the post data. I'm using simple_example as a guide.

To Reproduce
To reproduce the bug get the project in https://github.com/NakedSolidSnake/C_Webserver_Registry
I'm using postman to send message in POST
endpoint: /insert
data: fname=Name&faddress=Address&fage=42

Expected behavior
I want to get variable values

System (please complete the following information):
AME="Linux Mint"
VERSION="19.1 (Tessa)"
ID=linuxmint
ID_LIKE=ubuntu
PRETTY_NAME="Linux Mint 19.1"
VERSION_ID="19.1"
HOME_URL="https://www.linuxmint.com/"
SUPPORT_URL="https://forums.ubuntu.com/"
BUG_REPORT_URL="http://linuxmint-troubleshooting-guide.readthedocs.io/en/latest/"
PRIVACY_POLICY_URL="https://www.linuxmint.com/"
VERSION_CODENAME=tessa
UBUNTU_CODENAME=bionic

Additional context
Thread 3 "MHD-connection" hit Breakpoint 1, callback_insert (request=0x7fffe4000b70, response=0x7fffe4001900, user_data=0x0)
at /media/cssouza/SOLIDCRIS/repositories/C_Language/C_Webserver_Registry/src/main.c:73
73 char *url_params = print_map(request->map_url);
(gdb) p *request
$1 = {http_protocol = 0x7fffe4000e90 "HTTP/1.1", http_verb = 0x7fffe4000eb0 "POST", http_url = 0x7fffe4000e10 "/insert", url_path = 0x0,
proxy = 0x1 <error: Cannot access memory at address 0x1>, network_type = 0, check_server_certificate = 0, check_server_certificate_flag = -469758256, check_proxy_certificate = 32767,
check_proxy_certificate_flag = 0, follow_redirect = 0, ca_path = 0x0, timeout = 140737018596336, client_address = 0x7fffe4000c20, auth_basic_user = 0x7fffe4000c50 "",
auth_basic_password = 0x7fffe4000c80 "", map_url = 0x7fffe4000fb0, map_header = 0x27, map_cookie = 0x35, map_post_body = 0x0, binary_body = 0x7fffe4000cd0,
binary_body_length = 140737018596528, callback_position = 3959459072, client_cert = 0x0, client_cert_file = 0x35 <error: Cannot access memory at address 0x35>,
client_key_file = 0xd <error: Cannot access memory at address 0xd>, client_key_password = 0x7fffe40016c0 "\360\016"}
(gdb) c
Continuing.

Thread 3 "MHD-connection" received signal SIGSEGV, Segmentation fault.
0x0000555555554fa5 in print_map (map=0x7fffe4000fb0) at /media/cssouza/SOLIDCRIS/repositories/C_Language/C_Webserver_Registry/src/main.c:20
20 for (i=0; keys[i] != NULL; i++) {
(gdb) bt
#0 0x0000555555554fa5 in print_map (map=0x7fffe4000fb0) at /media/cssouza/SOLIDCRIS/repositories/C_Language/C_Webserver_Registry/src/main.c:20
#1 0x000055555555501a in callback_insert (request=0x7fffe4000b70, response=0x7fffe4001900, user_data=0x0)
at /media/cssouza/SOLIDCRIS/repositories/C_Language/C_Webserver_Registry/src/main.c:73
#2 0x00007ffff7bc6e21 in ?? () from /usr/lib/libulfius.so.2.2
#3 0x00007ffff73b45f5 in ?? () from /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.12
#4 0x00007ffff73b61a8 in ?? () from /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.12
#5 0x00007ffff73b8016 in ?? () from /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.12
#6 0x00007ffff73bb558 in ?? () from /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.12
#7 0x00007ffff6f946db in start_thread (arg=0x7ffff0e38700) at pthread_create.c:463
#8 0x00007ffff76ee88f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

[babelouest]

Hello @NakedSolidSnake ,

I can't reproduce your bug by using your code and executing the curl command:

$ curl -i --data "fname=Name&faddress=Address&fage=42" http://localhost:8095/insert
HTTP/1.1 200 OK
Connection: Keep-Alive
Content-Length: 0
Access-Control-Allow-Origin: *
Date: Sun, 07 Feb 2021 14:26:28 GMT

Besides the fact that your issue is in a useless part of the code in your case (you don't use url_params anywhere after setting it), there is no problem with your code that could lead to a segfault. I believe your problem is elsewhere.

How did you install ulfius? did you compile from the source? Or install a package downloaded from github? Or something else?
If you installed a package that may be the problem: there is no package for Linux Mint.
I suggest to build ulfius from the source and retry.

[NakedSolidSnake]

How did you install ulfius?
did you compile from the source?
Or install a package downloaded from github? Or something else?
R: I downloaded from github, compiled and installed.
If you installed a package that may be the problem: there is no package for Linux Mint.
I suggest to build ulfius from the source and retry.
C: Yeah I tried both, but no one works fine, maybe can be the operation system flavor, I'll try in another.
But there is some strange about addresses showed in gdb when I printed variable request. Is there somewhere that I need to initialize the request buffers to works fine?
I saw in the samples there is no need. But who knows?

[NakedSolidSnake]

Yeah, You're right. Doesn't work in that Linux flavor. I ran on my raspberry pi works fine. Thanks for your attention.

[babelouest]

Thanks for the confirmation, I'll try to test it with a Linux Mint to try to reproduce the problem.