[PATCH] Fix potential use after free in uidswap.c (portable)

[Darren Tucker]

On Sun, Jun 21, 2015 at 12:31 AM, Albert S. <mail at quitesimple.org> wrote:

> Fixes a potential (but probably rather unlikely) use after free bug in
> function temporarily_use_uid(), file uidswap.c.
>

Does seem unlikely (with zero entries there's no reason for it to deref the
pointer), however reading the man pages it seems like there's no guarantee
that it won't, so seems reasonable to me.  Damien?


> --- a/uidswap.c
> +++ b/uidswap.c
> @@ -113,8 +113,9 @@ temporarily_use_uid(struct passwd *pw)
>                 }
>         }
>         /* Set the effective uid to the given (unprivileged) uid. */
> -       if (setgroups(user_groupslen, user_groups) < 0)
> -               fatal("setgroups: %.100s", strerror(errno));
> +       if (user_groupslen > 0 &&
> +            (setgroups(user_groupslen, user_groups)) < 0)
> +               fatal("setgroups: %.100s", strerror(errno));
>
> Best regards,
> Albert
> _______________________________________________
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> openssh-unix-dev at mindrot.org
> https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
>



-- 
Darren Tucker (dtucker at zip.com.au)
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