Re: Use after free in __dst_destroy_metrics_generic

On Sat, Sep 16, 2017 at 5:40 AM, Julian Anastasov [off-list ref] wrote:

        Hello,

On Fri, 15 Sep 2017, Subash Abhinov Kasiviswanathan wrote:

quoted

quoted

    May be I'm missing some posting but I don't see if
the patch was tested successfully.

Hi Julian

I've had this patch being tested for the last 3-4 days in our regression rack
and I haven't seen the same issue being reproduced or even a related crash
or leak in dst.

        For now I see only its bug-hiding side effects, i.e.
it does not call kfree. Now if there is no double-free
there should be a leak, not for dst but for metrics.

You make very good points. I need to take a deeper look.

quoted

The original issue was reported only once to us from the regression rack only
so the exact steps to reproduce is unknown.

        OK, lets see, may be others can explain what happens.

This makes me thinking if it is possible that we no longer have
the guarantee of metrics address aligned to at least 4?
This seems unlikely since kmalloc() should return at least
word-size-aligned address.