linux-kernel - Re: [PATCH 167/190] Revert "gdrom: fix a memory leak bug"

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Date:   Tue, 27 Apr 2021 18:11:24 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Peter Rosin <peda@...ntia.se>
Cc:     Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 167/190] Revert "gdrom: fix a memory leak bug"

On Tue, Apr 27, 2021 at 04:03:01PM +0200, Peter Rosin wrote:
> On 2021-04-27 15:01, Greg KH wrote:
> > On Fri, Apr 23, 2021 at 08:20:30AM -0600, Jens Axboe wrote:
> >> On 4/22/21 3:29 PM, Peter Rosin wrote:
> >>>> This reverts commit 093c48213ee37c3c3ff1cf5ac1aa2a9d8bc66017.
> >>>
> >>> The reverted patch looks fishy.
> >>>
> >>> gc.cd_info is kzalloc:ed on probe. In case probe fails after this allocation, the
> >>> memory is kfree:d but the variable is NOT zeroed out.
> >>>
> >>> AFAICT, the above leads to a double-free on exit by the added line.
> >>>
> >>> I believe gd.cd_info should be kfree:d on remove instead.
> >>>
> >>> However, might not gc.toc also be kfree:d twice for similar reasons?
> >>>
> >>> I could easily be mistaken.
> >>
> >> >From taking a quick look the other day, that's my conclusion too. I
> >> don't think the patch is correct, but I don't think the surrounding code
> >> is correct right now either.
> > 
> > Thanks for the review from both of you, I'll keep this commit in the
> > tree.
> Err, which commit is "this" and what tree are you keeping it in? I
> think you mean that you are keeping the revert in your tree with
> reverts, and not that you mean that we should keep the original
> commit in Linus' tree.

That is correct, I will be keeping this revert in my tree.

> In any case, I'd think that the original memory leak is somewhat
> better than the introduced double-free and therefore the revert
> should be done.

Will do that.

thanks,

greg k-h