From: "Alex Bennée" <alex.bennee@linaro.org>
To: "Philippe Mathieu-Daudé" <philmd@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>,
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>,
"Daniel P . Berrange" <berrange@redhat.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 11:10:31 +0000 [thread overview]
Message-ID: <87v8zneap1.fsf@linaro.org> (raw)
In-Reply-To: <34bd86db-a213-bb3a-9c72-8c48bd138835@redhat.com>
Philippe Mathieu-Daudé <philmd@redhat.com> writes:
> On 12/16/21 15:11, 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").
>>>
<snip>
>>> +#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)?
>
> I followed the documentation in include/glib-compat.h:
>
> /*
> * Note that because of the GLIB_VERSION_MAX_ALLOWED constant above,
> allowing
> * use of functions from newer GLib via this compat header needs a little
> * trickery to prevent warnings being emitted.
> *
> * Consider a function from newer glib-X.Y that we want to use
> *
> * int g_foo(const char *wibble)
> *
> * We must define a static inline function with the same signature that does
> * what we need, but with a "_qemu" suffix e.g.
> *
> * static inline void g_foo_qemu(const char *wibble)
> * {
> * #if GLIB_CHECK_VERSION(X, Y, 0)
> * g_foo(wibble)
> * #else
> * g_something_equivalent_in_older_glib(wibble);
> * #endif
> * }
> *
> * The #pragma at the top of this file turns off -Wdeprecated-declarations,
> * ensuring this wrapper function impl doesn't trigger the compiler warning
> * about using too new glib APIs. Finally we can do
> *
> * #define g_foo(a) g_foo_qemu(a)
> *
> * So now the code elsewhere in QEMU, which *does* have the
> * -Wdeprecated-declarations warning active, can call g_foo(...) as normal,
> * without generating warnings.
> */
>
> which is how g_unix_get_passwd_entry_qemu() is implemented.
Yet later we have qemu_g_test_slow following the style guide. Also I'm
confused by the usage of g_unix_get_passwd_entry_qemu because the only
place I see it in qga/commands-posix-ssh.c right before it does:
#define g_unix_get_passwd_entry_qemu(username, err) \
test_get_passwd_entry(username, err)
although I think that only hold when the file is built with
QGA_BUILD_UNIT_TEST.
> Should we reword the documentation first?
The original wording in glib-compat.h was added by Daniel in 2018 but
the commit that added the password function comments:
Since the fallback version is still unsafe, I would rather keep the
_qemu postfix, to make sure it's not being misused by mistake. When/if
necessary, we can implement a safer fallback and drop the _qemu suffix.
So if we are going to make a distinction between a qemu prefix and
suffix we should agree that and add it to the style document.
--
Alex Bennée
next prev parent reply other threads:[~2021-12-17 11:26 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 [this message]
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
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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