[Dnsmasq-discuss] [PATCH] Various fixes detected by static analysis

[Simon Kelley]

On 21/08/18 21:22, Petr Mensik wrote:
> Hi Simon and all others,
> 
> I have tried running dnsmasq under coverity, static analysis tool. It
> found some warnings. I have fixed some things. Most obvious error was
> inconsistent handling of buffer length of interface names. Buffer size
> is IFNAMSIZ long, that is 16 bytes. But if interface should have
> terminating zero, max. useable length is 15. Sometimes, buffer size is
> 16+1, sometimes only 16. Sometimes name might be sent to the kernel
> unterminated. According to [1] it cannot be longer in Linux.
> 
> I have created shared simple function that will always terminate string.
> And few little improvements around. What do you think?


Looks good on first look. I'll find time to go through it in more detail
and apply it soon.
> 
> It complains a lot about returns from one_opt in option.c. I can make
> patch that will deallocate memory before returning error. In some cases,
> i think option parsing does not have to be fatal. Would you accept fixes
> that will free memory before return? I think in some cases option
> parsing can be used for files that can be reread multiple times when
> running.

The only code where an error is not fatal is for dhcp-option, dhcp-host,
server and rev-server which get called when files containing just those
options are read dynamically. That means parse_dhcp_opt() and code
starting at 3025, 2401 and 2493
I suspect there are therefore memory leaks in those which might be worth
fixing. For the vast majority of errors in one_opt, they are fatal, and
complicating the code massively to avoid warnings from coverity is
probably not a good move.


Cheers,

Simon.



> 
> 1.
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/diff/?id=f236da93df5be85409c24f03683e3d8c54fac72b
> 
> 
> 
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