From: "Alex Bennée" <alex.bennee@linaro.org>
To: "Daniel P. Berrangé" <berrange@redhat.com>
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Jason Wang" <jasowang@redhat.com>,
"Christian Schoenebeck" <qemu_oss@crudebyte.com>,
qemu-devel@nongnu.org, "Gerd Hoffmann" <kraxel@redhat.com>,
"Eric Blake" <eblake@redhat.com>,
qemu-block@nongnu.org, "David Hildenbrand" <david@redhat.com>,
"Markus Armbruster" <armbru@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>,
"Laurent Vivier" <lvivier@redhat.com>,
"Thomas Huth" <thuth@redhat.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
qemu-arm@nongnu.org, "John Snow" <jsnow@redhat.com>,
"David Gibson" <david@gibson.dropbear.id.au>,
"Kevin Wolf" <kwolf@redhat.com>,
"Vladimir Sementsov-Ogievskiy" <vsementsov@virtuozzo.com>,
"Hanna Reitz" <hreitz@redhat.com>,
qemu-ppc@nongnu.org, "Paolo Bonzini" <pbonzini@redhat.com>
Subject: Re: [PATCH v3 02/28] glib-compat: Introduce g_memdup2() wrapper
Date: Fri, 17 Dec 2021 14:53:05 +0000 [thread overview]
Message-ID: <87ilvne0x2.fsf@linaro.org> (raw)
In-Reply-To: <YbyT7D/UpSGpmC24@redhat.com>
Daniel P. Berrangé <berrange@redhat.com> writes:
> On Thu, Dec 16, 2021 at 02:11:37PM +0000, Alex Bennée wrote:
>>
>> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
>>
>> > When experimenting raising GLIB_VERSION_MIN_REQUIRED to 2.68
>> > (Fedora 34 provides GLib 2.68.1) we get:
>> >
>> > hw/virtio/virtio-crypto.c:245:24: error: 'g_memdup' is deprecated: Use 'g_memdup2' instead [-Werror,-Wdeprecated-declarations]
>> > ...
>> >
>> > g_memdup() has been updated by g_memdup2() to fix eventual security
>> > issues (size argument is 32-bit and could be truncated / wrapping).
>> > GLib recommends to copy their static inline version of g_memdup2():
>> > https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538
>> >
>> > Our glib-compat.h provides a comment explaining how to deal with
>> > these deprecated declarations (see commit e71e8cc0355
>> > "glib: enforce the minimum required version and warn about old APIs").
>> >
>> > Following this comment suggestion, implement the g_memdup2_qemu()
>> > wrapper to g_memdup2(), and use the safer equivalent inlined when
>> > we are using pre-2.68 GLib.
>> >
>> > Reported-by: Eric Blake <eblake@redhat.com>
>> > Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> > ---
>> > include/glib-compat.h | 37 +++++++++++++++++++++++++++++++++++++
>> > 1 file changed, 37 insertions(+)
>> >
>> > diff --git a/include/glib-compat.h b/include/glib-compat.h
>> > index 9e95c888f54..8d01a8c01fb 100644
>> > --- a/include/glib-compat.h
>> > +++ b/include/glib-compat.h
>> > @@ -68,6 +68,43 @@
>> > * without generating warnings.
>> > */
>> >
>> > +/*
>> > + * g_memdup2_qemu:
>> > + * @mem: (nullable): the memory to copy.
>> > + * @byte_size: the number of bytes to copy.
>> > + *
>> > + * Allocates @byte_size bytes of memory, and copies @byte_size bytes into it
>> > + * from @mem. If @mem is %NULL it returns %NULL.
>> > + *
>> > + * This replaces g_memdup(), which was prone to integer overflows when
>> > + * converting the argument from a #gsize to a #guint.
>> > + *
>> > + * This static inline version is a backport of the new public API from
>> > + * GLib 2.68, kept internal to GLib for backport to older stable releases.
>> > + * See https://gitlab.gnome.org/GNOME/glib/-/issues/2319.
>> > + *
>> > + * Returns: (nullable): a pointer to the newly-allocated copy of the memory,
>> > + * or %NULL if @mem is %NULL.
>> > + */
>> > +static inline gpointer g_memdup2_qemu(gconstpointer mem, gsize byte_size)
>> > +{
>> > +#if GLIB_CHECK_VERSION(2, 68, 0)
>> > + return g_memdup2(mem, byte_size);
>> > +#else
>> > + gpointer new_mem;
>> > +
>> > + if (mem && byte_size != 0) {
>> > + new_mem = g_malloc(byte_size);
>> > + memcpy(new_mem, mem, byte_size);
>> > + } else {
>> > + new_mem = NULL;
>> > + }
>> > +
>> > + return new_mem;
>> > +#endif
>> > +}
>> > +#define g_memdup2(m, s) g_memdup2_qemu(m, s)
>> > +
>>
>> As per our style wouldn't it make sense to just call it qemu_memdup(m,
>> s)?
>
> Not in this case. We use suffix as we don't want people calling this
> directly with the suffix.
>
> In the glibcompat.h header we're attempting to transparently/secretly
> replace/wrap standard glib APIs. All the callers should remain using
> the plain glib API name, never call the method with the suffix at
> all. This lets us delete the wrapper later and not have to update
> any callers. The suffix is basically just a hack of the impl we use
> for transparent replacement.
Right - at the risk of bike shedding names maybe we should choose a
suffix the better reflects the purpose like _alt or _internal rather
than overloading qemu?
We already document _locked for example.
> A method with a 'qemu_' prefix by constrast is something that callers
> are explicitly expected to call directly.
>
>
> Regards,
> Daniel
--
Alex Bennée
next prev parent reply other threads:[~2021-12-17 15:28 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-03 17:44 [PATCH v3 00/28] glib: Replace g_memdup() by g_memdup2() Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 01/28] hw/hyperv/vmbus: Remove unused vmbus_load/save_req() Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 02/28] glib-compat: Introduce g_memdup2() wrapper Philippe Mathieu-Daudé
2021-09-03 20:37 ` Eric Blake
2021-12-16 14:11 ` Alex Bennée
2021-12-16 18:39 ` Philippe Mathieu-Daudé
2021-12-17 11:10 ` Alex Bennée
2021-12-17 11:41 ` Laurent Vivier
2021-12-17 12:15 ` Alex Bennée
2021-12-17 13:39 ` Daniel P. Berrangé
2021-12-17 13:43 ` Daniel P. Berrangé
2021-12-17 14:53 ` Alex Bennée [this message]
2021-12-17 15:01 ` Daniel P. Berrangé
2021-12-17 10:55 ` Laurent Vivier
2021-09-03 17:44 ` [PATCH v3 03/28] qapi: Replace g_memdup() by g_memdup2() Philippe Mathieu-Daudé
2021-09-03 21:10 ` Eric Blake
2021-09-03 17:44 ` [PATCH v3 04/28] accel/tcg: " Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 05/28] block/qcow2-bitmap: " Philippe Mathieu-Daudé
2021-09-03 21:13 ` Eric Blake
2021-09-03 21:14 ` Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 06/28] softmmu: " Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 07/28] hw/9pfs: " Philippe Mathieu-Daudé
2021-09-04 12:25 ` Christian Schoenebeck
2021-09-03 17:44 ` [PATCH v3 08/28] hw/acpi: Avoid truncating acpi_data_len() to 32-bit Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 09/28] hw/acpi: Replace g_memdup() by g_memdup2() Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 10/28] hw/core/machine: " Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 11/28] hw/hppa/machine: " Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 12/28] hw/i386/multiboot: " Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 13/28] hw/net/eepro100: " Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 14/28] hw/nvram/fw_cfg: " Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 15/28] hw/scsi/mptsas: " Philippe Mathieu-Daudé
2021-09-03 17:44 ` [PATCH v3 16/28] hw/ppc/spapr_pci: " Philippe Mathieu-Daudé
2021-09-04 3:38 ` David Gibson
2021-09-03 17:44 ` [PATCH v3 17/28] hw/rdma: " Philippe Mathieu-Daudé
2021-09-03 17:45 ` [PATCH v3 18/28] hw/vfio/pci: " Philippe Mathieu-Daudé
2021-09-03 17:45 ` [RFC PATCH v3 19/28] hw/virtio: " Philippe Mathieu-Daudé
2022-04-01 10:50 ` Eugenio Perez Martin
2021-09-03 17:45 ` [PATCH v3 20/28] net/colo: " Philippe Mathieu-Daudé
2021-09-03 17:45 ` [RFC PATCH v3 21/28] ui/clipboard: " Philippe Mathieu-Daudé
2021-09-03 17:45 ` [RFC PATCH v3 22/28] linux-user: " Philippe Mathieu-Daudé
2021-09-03 17:45 ` [PATCH v3 23/28] tests/unit: " Philippe Mathieu-Daudé
2021-09-03 17:45 ` [PATCH v3 24/28] tests/qtest: " Philippe Mathieu-Daudé
2021-09-04 5:48 ` Thomas Huth
2021-12-17 10:56 ` Laurent Vivier
2021-09-03 17:45 ` [PATCH v3 25/28] target/arm: " Philippe Mathieu-Daudé
2021-09-03 17:45 ` [PATCH v3 26/28] target/ppc: " Philippe Mathieu-Daudé
2021-09-04 3:38 ` David Gibson
2021-09-03 17:45 ` [PATCH v3 27/28] contrib: " Philippe Mathieu-Daudé
2021-09-03 17:45 ` [PATCH v3 28/28] checkpatch: Do not allow deprecated g_memdup() Philippe Mathieu-Daudé
2021-09-03 21:17 ` Eric Blake
2021-12-17 10:58 ` Laurent Vivier
2021-12-15 16:54 ` [PATCH v3 00/28] glib: Replace g_memdup() by g_memdup2() Philippe Mathieu-Daudé
2021-12-17 10:59 ` Laurent Vivier
2024-05-08 21:22 ` Philippe Mathieu-Daudé
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