[asterisk-bugs] [JIRA] (ASTERISK-20858) app_minivm fails to clean up mkstemp files

[Matt Jordan (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-20858?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=201057#comment-201057 ] 

Matt Jordan commented on ASTERISK-20858:
----------------------------------------

So, my only defense here is that I didn't introduce (a) or (b) :-)

It looks like what you described is actual the original intent of the code - to use mkstemp for the unique string of characters it produces as an input to {{sox}}, as opposed to actually using the file it creates. You're right that it probably shouldn't do that and that it should at least clean up the 0 byte file it just created on disk.

I don't think you're very likely to have a filename collision by appending '.wav' to ABCDEF when you call {{sox}}, but it  is possible.
                
> app_minivm fails to clean up mkstemp files
> ------------------------------------------
>
>                 Key: ASTERISK-20858
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-20858
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Applications/app_minivm
>            Reporter: Walter Doekes
>            Severity: Minor
>
> Matt recently touched this code and removed a comment about leaking fd's and files.
> {noformat}
>                 tmpfd = mkstemp(newtmp);
>                 if (tmpfd < 0) {
>                         ast_log(LOG_WARNING, "Failed to create temporary file for volgain: %d\n", errno);
>                         ast_free(str1);
>                         ast_free(str2);
>                         return -1;
>                 }
>                 snprintf(tmpcmd, sizeof(tmpcmd), "sox -v %.4f %s.%s %s.%s", vmu->volgain, filename, format, newtmp, format);
>                 ast_safe_system(tmpcmd);
> {noformat}
> The fd leaks may be gone, but this looks like:
> (a) file leaks
> (b) misuse of mkstemp by appending format to the filename
> First we have mkstemp create an actual file "/tmp/ABCDEF" and then we write to "/tmp/ABCDEF.wav". No one cares about the original "/tmp/ABCDEF" on disk, and by writing to "/tmp/ABCDEF.wav" you're ignoring most of the functionality of mkstemp -- being secure and not overwriting existing files.
> Lastly, no one ever clears up fname (finalfilename.format), resulting in a second file leak.

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