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[83.52.55.21]) by smtp.gmail.com with ESMTPSA id y4sm394108wmi.22.2021.09.03.14.14.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 03 Sep 2021 14:14:52 -0700 (PDT) Subject: Re: [PATCH v3 05/28] block/qcow2-bitmap: Replace g_memdup() by g_memdup2() To: Eric Blake References: <20210903174510.751630-1-philmd@redhat.com> <20210903174510.751630-6-philmd@redhat.com> <20210903211322.n5isnkxin6jlkxrf@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: <51de5796-3137-6ac3-c935-eb097fc4ca45@redhat.com> Date: Fri, 3 Sep 2021 23:14:51 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210903211322.n5isnkxin6jlkxrf@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=philmd@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.392, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.888, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001, T_SPF_HELO_TEMPERROR=0.01 autolearn=unavailable autolearn_force=no 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: Peter Maydell , "Michael S. Tsirkin" , Jason Wang , Christian Schoenebeck , qemu-devel@nongnu.org, Gerd Hoffmann , qemu-block@nongnu.org, John Snow , David Hildenbrand , Markus Armbruster , Laurent Vivier , Thomas Huth , Eduardo Habkost , Richard Henderson , qemu-arm@nongnu.org, =?UTF-8?Q?Alex_Benn=c3=a9e?= , David Gibson , Kevin Wolf , Vladimir Sementsov-Ogievskiy , "Daniel P . Berrange" , Hanna Reitz , qemu-ppc@nongnu.org, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/3/21 11:13 PM, Eric Blake wrote: > On Fri, Sep 03, 2021 at 07:44:47PM +0200, Philippe Mathieu-Daudé wrote: >> Per https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538 >> >> The old API took the size of the memory to duplicate as a guint, >> whereas most memory functions take memory sizes as a gsize. This >> made it easy to accidentally pass a gsize to g_memdup(). For large >> values, that would lead to a silent truncation of the size from 64 >> to 32 bits, and result in a heap area being returned which is >> significantly smaller than what the caller expects. This can likely >> be exploited in various modules to cause a heap buffer overflow. >> >> Replace g_memdup() by the safer g_memdup2() wrapper. >> >> Signed-off-by: Philippe Mathieu-Daudé >> --- >> block/qcow2-bitmap.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c >> index 8fb47315515..218a0dc712a 100644 >> --- a/block/qcow2-bitmap.c >> +++ b/block/qcow2-bitmap.c >> @@ -1599,7 +1599,7 @@ bool qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, >> name); >> goto fail; >> } >> - tb = g_memdup(&bm->table, sizeof(bm->table)); >> + tb = g_memdup2(&bm->table, sizeof(bm->table)); > > Trivially safe. It might be worth a comment in the various commit > messages for which patches are trivially safe (because the argument > was directly from sizeof), and which would require a larger audit of > callers to see if we had any (unlikely) bug (such as patch 3/28). Yes, will do. > Reviewed-by: Eric Blake Thanks!