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Thu, 2 Jul 2020 08:14:26 +0000 (UTC) Subject: Re: [PATCH 1/4] migration: Prevent memleak by ...params_test_apply To: Eric Blake , qemu-block@nongnu.org References: <20200630084552.46362-1-mreitz@redhat.com> <20200630084552.46362-2-mreitz@redhat.com> <1e801600-db27-1625-f168-1b08396dc5b2@redhat.com> From: Max Reitz Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: <501a06fb-6c53-d607-5af9-86450f6c2c7b@redhat.com> Date: Thu, 2 Jul 2020 10:14:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <1e801600-db27-1625-f168-1b08396dc5b2@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="lHKA3QIeDq7FWPoFmn5wSrNEYsMD9bxLv" Received-SPF: pass client-ip=205.139.110.120; envelope-from=mreitz@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/02 04:00:43 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Peter Krempa , Juan Quintela , Markus Armbruster , qemu-devel@nongnu.org, "Dr . David Alan Gilbert" , Vladimir Sementsov-Ogievskiy Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --lHKA3QIeDq7FWPoFmn5wSrNEYsMD9bxLv Content-Type: multipart/mixed; boundary="XEee7d3o3Ts3RC3bNs91OhVpPVuyZkS3X" --XEee7d3o3Ts3RC3bNs91OhVpPVuyZkS3X Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 01.07.20 16:38, Eric Blake wrote: > On 6/30/20 3:45 AM, Max Reitz wrote: >> The created structure is not really a proper QAPI object, so we cannot >> and will not free its members.=C2=A0 Strings therein should therefore no= t be >> duplicated, or we will leak them. >=20 > This seems fragile to me; having to code QAPI usage differently > depending on whether the containing struct was malloc'd or not (and > therefore whether someone will call qapi_free_MigrateSetParameters or > not) looks awkward to maintain. I don=E2=80=99t think that=E2=80=99s the point. The point is that it=E2=80= =99s just a temporary object to run some check function on. This is a very... special use case. > We have > visit_type_MigrateSetParameters_members, could that be used as a cleaner > way to free all members of the struct without freeing the struct itself? > =C2=A0Should the QAPI generator start generating qapi_free_FOO_members to > make such cleanup easier? The whole code is a mess, in my opinion. The real question is why don=E2=80=99t we just drop migrate_params_test_app= ly() and let qmp_migrate_set_parameters() invoke migrate_params_check() directly on @params. I think there was some reason why I didn=E2=80=99t do that, but unfortunate= ly I don=E2=80=99t remember it off the top of my head (if there was a reason). In any case, I don=E2=80=99t think any of this is the QAPI generator=E2=80= =99s fault. >> Signed-off-by: Max Reitz >> --- >> =C2=A0 migration/migration.c | 4 ++-- >> =C2=A0 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/migration/migration.c b/migration/migration.c >> index 481a590f72..47c7da4e55 100644 >> --- a/migration/migration.c >> +++ b/migration/migration.c >> @@ -1336,12 +1336,12 @@ static void >> migrate_params_test_apply(MigrateSetParameters *params, >> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (params->has_tls_creds) { >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 assert(params->tl= s_creds->type =3D=3D QTYPE_QSTRING); >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 dest->tls_creds =3D g_strdup= (params->tls_creds->u.s); >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 dest->tls_creds =3D params->= tls_creds->u.s; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (params->has_tls_hostname) { >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 assert(params->tl= s_hostname->type =3D=3D QTYPE_QSTRING); >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 dest->tls_hostname =3D g_str= dup(params->tls_hostname->u.s); >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 dest->tls_hostname =3D param= s->tls_hostname->u.s; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (params->has_max_bandwidth) { >> >=20 --XEee7d3o3Ts3RC3bNs91OhVpPVuyZkS3X-- --lHKA3QIeDq7FWPoFmn5wSrNEYsMD9bxLv Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl79l2EACgkQ9AfbAGHV z0B1ywf+JjUBAhBuTNOhL1nJFplyZ06KVGNj2ufTOsncU5cA7ecSFkASsUN7rIki MFIafwVxuS+2OV9fwEjvJjXJnQtf/U1FGM/HhjFmXzdEFSXReXa/AfupTjMCO4Yu FoVD7YLJWBd8lcqLtneg5cTQgVwtb4+IS96oFgUjSn76BcanOFZ1dTCs4ZwmzMau GY5o9f8OWN++wehlSBHes7eSPbOlSvn3NGoyvO3iT19NlT83qevLRe1EIVtAyrLV O/MtEJfTrBkazBLtUxUG0D4Q8V6w8wNyK+8ZNs9ONaOzCT95KNJCA24X6p+JA0xF eoldfMbE0SVlaBZ5T/0tJ1AicSDO0A== =ao4S -----END PGP SIGNATURE----- --lHKA3QIeDq7FWPoFmn5wSrNEYsMD9bxLv--