[
https://issues.apache.org/jira/browse/GUACAMOLE-608?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Michael Jumper updated GUACAMOLE-608:
-------------------------------------
Description:
{{guacd}} involves a {{__write_all}} function to write instruction as much as
possible, see
https://github.com/apache/guacamole-server/blob/7c191d7be0441a1cb64c90ab62d6535f3798eacb/src/guacd/connection.c#L67
However system call {{write}} may return 0 and set {{errno}}, which is not
verified in the function.
A possible case: {{write}} keeps return 0 and nothing writes to buffer,
therefore the daemon process encounters a dead loop, furthermore, it leads CPU
rate up to 99%.
A possible fix is:
{code:none}
int written = write(fd, buffer, length);
if (written < 0 || errno > 0)
return -1;
{code}
was:
`guacd` involves a `__write_all` function to write instruction as much as
possible, see
https://github.com/apache/guacamole-server/blob/7c191d7be0441a1cb64c90ab62d6535f3798eacb/src/guacd/connection.c#L67
However system call `write` may return 0 and set `errno`, which is not verified
in the function.
A possible case: `write` keeps return 0 and nothing writes to buffer, therefore
the daemon process encounters a dead loop, furthermore, it leads CPU rate up to
99%.
A possible fix is:
```
int written = write(fd, buffer, length);
if (written < 0 || errno > 0)
return -1;
```
> Daemon process may encounter dead loop
> --------------------------------------
>
> Key: GUACAMOLE-608
> URL: https://issues.apache.org/jira/browse/GUACAMOLE-608
> Project: Guacamole
> Issue Type: Bug
> Components: guacd
> Affects Versions: 0.9.14, 1.0.0
> Reporter: Changkun Ou
> Priority: Major
>
> {{guacd}} involves a {{__write_all}} function to write instruction as much as
> possible, see
> https://github.com/apache/guacamole-server/blob/7c191d7be0441a1cb64c90ab62d6535f3798eacb/src/guacd/connection.c#L67
> However system call {{write}} may return 0 and set {{errno}}, which is not
> verified in the function.
> A possible case: {{write}} keeps return 0 and nothing writes to buffer,
> therefore the daemon process encounters a dead loop, furthermore, it leads
> CPU rate up to 99%.
> A possible fix is:
> {code:none}
> int written = write(fd, buffer, length);
> if (written < 0 || errno > 0)
> return -1;
> {code}
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