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From: Andrew Morton on 15 Mar 2010 16:50
On Mon, 15 Mar 2010 11:26:56 +0300
Dan Carpenter <error27(a)gmail.com> wrote:

> adpt_i2o_delete_hba() calls kfree() so we have to save "pHba->next"
> before calling it. Also inside adpt_i2o_delete_hba() itself, there
> was another use after free bug which I fixed by moving the kfree()
> down a line.

erk. This code should be crashing most gruesomely. I wonder why it
doesn't.

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From: James Bottomley on 15 Mar 2010 18:50
On Mon, 2010-03-15 at 13:45 -0700, Andrew Morton wrote:
> On Mon, 15 Mar 2010 11:26:56 +0300
> Dan Carpenter <error27(a)gmail.com> wrote:
>
> > adpt_i2o_delete_hba() calls kfree() so we have to save "pHba->next"
> > before calling it. Also inside adpt_i2o_delete_hba() itself, there
> > was another use after free bug which I fixed by moving the kfree()
> > down a line.
>
> erk. This code should be crashing most gruesomely. I wonder why it
> doesn't.

I'm tempted to say because we have no users, but actually, for this
driver, I know we do. So I think it works because most people don't
have poisoning turned on in a running system and there's no sleep
between the free and the use, so no opportunity to reuse the area on the
percpu hot list even in an smp system.

I'll add it to -rc fixes ... when I get the current misc tree broken
apart.

James


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