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Date: Thu, 5 Jul 2018 18:21:00 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] block/crypto: Simplify
 block_crypto_co_create_opts_luks to avoid a memory leak
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To: Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= <f4bug@amsat.org>
Cc: Max Reitz <mreitz@redhat.com>, qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, qemu-block@nongnu.org, Markus Armbruster <armbru@redhat.com>, Eric Blake <eblake@redhat.com>

Am 05.07.2018 um 18:04 hat Philippe Mathieu-Daud=E9 geschrieben:
> On 07/05/2018 07:20 AM, Kevin Wolf wrote:
> > Am 04.07.2018 um 17:02 hat Philippe Mathieu-Daud=E9 geschrieben:
> >> After 1ec4f4160a1 Coverity reported:
> >>
> >>   Variable cryptoopts going out of scope leaks the storage it points=
 to.
> >>
> >> Fixes: Coverity CID 1393782 (Resource leak)
> >> Signed-off-by: Philippe Mathieu-Daud=E9 <f4bug@amsat.org>
> >=20
> > I already sent a much simpler fix:
> > [PATCH] block/crypto: Fix memory leak in create error path
>=20
> Oh OK I searched a bit but missed it.
>=20
> > The only thing that is needed is replacing the return with a goto.
> > Splitting it in three different error paths is unnecessary because th=
e
> > cleanup function handle NULL values just fine.
>=20
> OK, good to know.
>=20
> >> I think this check is superfluous but I respected the previous code:
> >>
> >>      ret =3D block_crypto_co_create_generic(bs, size, create_opts, e=
rrp);
> >>      if (ret > 0) {
> >>          ret =3D 0;
> >>      }
> >=20
> > It is wrong, too. The old code keep the error code, goto fail skipped
> > the ret =3D 0.
>=20
> So this is not particularly wrong but as superfluous as the current use=
 :)
>=20
> ret =3D 0 is only useful if block_crypto_co_create_generic() returned a
> value > 0, which seems unlikely.

Sorry, yes, you're right. I read 'if (ret < 0)' in your patch.

The reason for the seemingly superfluous error path is that you can add
new code behind it without having to modify the existing code.

Kevin