RFR(xs): (jdk10) 8173828: realpath is unsafe

[Thomas Stüfe]

Hi Dmitry,

new webrev:
http://cr.openjdk.java.net/~stuefe/webrevs/8173828-realpath-is-unsafe/jdk10-webrev.02/webrev/

Fixed both issues. Note that os::jvm_path() does not have a way to signal
errors back to the caller. os::jvm_path has a number of issues and could
benefit from a cleanup, but this is outside the scope of this fix.

Thanks, Thomas


On Tue, Mar 14, 2017 at 12:30 PM, Dmitry Samersoff <
dmitry.samersoff at oracle.com> wrote:

> Thomas,
>
> > thank you for the review. These are good points, I addressed them all:
>
> os_posix.cpp:
>
>   1110: it's better to write as outbuf == NULL
>
> os_solaris.cpp:
>
>   2037: return value of realpath is not checked. Could you fix it as well?
>
> -Dmitry
>
>
> On 2017-03-14 14:19, Thomas Stüfe wrote:
> > Hi Dmitry,
> >
> > thank you for the review. These are good points, I addressed them all:
> >
> > New
> > webrev: http://cr.openjdk.java.net/~stuefe/webrevs/8173828-
> realpath-is-unsafe/jdk10-webrev.01/webrev/
> > Delta to
> > last: http://cr.openjdk.java.net/~stuefe/webrevs/8173828-
> realpath-is-unsafe/jdk10-webrev.00-to-01/webrev/
> >
> > Thanks, Thomas
> >
> > On Tue, Mar 14, 2017 at 10:00 AM, Dmitry Samersoff
> > <dmitry.samersoff at oracle.com <mailto:dmitry.samersoff at oracle.com>>
> wrote:
> >
> >     Thomas,
> >
> >     os_posix.cpp:
> >
> >     1121: It might be better to return ENAMETOOLONG
> >
> >     1131: It might be better to check for
> >           filename != NULL && outbuf != NULL before any call to realpath
> >           and return EINVAL for product and assert it for debug build.
> >
> >     1134: What is the goal of this assert? Do you see this problem?
> >
> >     1135: If realpath overwrites outbuf, strlen might have unpredictable
> >           effect.
> >
> >           So it might be better to set last byte of outbuf to 0 before
> >           call to realpath and check that it is still zero after call
> >
> >     -Dmitry
> >
> >     On 2017-03-14 10:11, Thomas Stüfe wrote:
> >     > Hi all,
> >     >
> >     > may I have reviews for this smallish fix.
> >     >
> >     > Issue: https://bugs.openjdk.java.net/browse/JDK-8173828
> >     <https://bugs.openjdk.java.net/browse/JDK-8173828>
> >     > Webrev:
> >     >
> >     http://cr.openjdk.java.net/~stuefe/webrevs/8173828-
> realpath-is-unsafe/jdk10-webrev.00/
> >     <http://cr.openjdk.java.net/~stuefe/webrevs/8173828-
> realpath-is-unsafe/jdk10-webrev.00/>
> >     >
> >     > In short, realpath(3) is unsafe the way it is traditionally used
> >     (with a
> >     > user buffer provided). It is safe if used in the new POSIX.1-2008
> >     compliant
> >     > way. To wrap this behavior, I added a new os::Posix::realpath()
> >     function
> >     > which takes a buffer and a buffer size (like a sane API would but
> the
> >     > ancient realpath() did not) and moved safe buffer handling into
> >     this API.
> >     >
> >     > Kind Regards, Thomas
> >     >
> >
> >
> >     --
> >     Dmitry Samersoff
> >     Oracle Java development team, Saint Petersburg, Russia
> >     * I would love to change the world, but they won't give me the
> sources.
> >
> >
>
>
> --
> Dmitry Samersoff
> Oracle Java development team, Saint Petersburg, Russia
> * I would love to change the world, but they won't give me the sources.
>