[PATCH] Do not leave random talloc magic in free()'ed memory, fix abort message

Volker Lendecke Volker.Lendecke at SerNet.DE
Wed Jan 17 09:14:32 UTC 2018

On Wed, Jan 17, 2018 at 09:33:59PM +1300, Andrew Bartlett via samba-technical wrote:
> In the context of DEBUG(), the attack is described here:
> https://www.owasp.org/index.php/Log_Injection
> For that reason, we took care to write and use log_escape() in the auth
> audit code.  It is declared here:
> lib/util/util_str_escape.c:char *log_escape(TALLOC_CTX *frame, const
> char *in)
> The list of 'bad' characters could potentially be extended.
> I don't know and didn't assert that printf("%s", untrusted) is itself
> unsafe, beyond the above I would see the main risk as being a SIGSEGV
> if the attacker can control the NUL termination.

Doing that manually is the wrong layer. We should do that directly in
DEBUG(). I know this essentially means writing our own printf, but
relying on everybody to correcly escape what's going into
%s is not going to work.


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