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Thu, 30 Jul 2020 10:25:09 +0000 (UTC) Date: Thu, 30 Jul 2020 11:25:06 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Halil Pasic Subject: Re: [PATCH 1/1] s390x/s390-virtio-ccw: fix off-by-one in loadparm getter Message-ID: <20200730102506.GD3477223@redhat.com> References: <20200729130222.29026-1-pasic@linux.ibm.com> MIME-Version: 1.0 In-Reply-To: <20200729130222.29026-1-pasic@linux.ibm.com> User-Agent: Mutt/1.14.5 (2020-06-23) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/30 03:41:52 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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=-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_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=ham 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Peter Maydell , Thomas Huth , David Hildenbrand , Cornelia Huck , qemu-devel@nongnu.org, Christian Borntraeger , qemu-s390x@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jul 29, 2020 at 03:02:22PM +0200, Halil Pasic wrote: > As pointed out by Peter, g_memdup(ms->loadparm, sizeof(ms->loadparm) + 1) > reads one past of the end of ms->loadparm, so g_memdup() can not be used > here. > > Let's use malloc and memcpy instead! > > Fixes: d664548328 ("s390x/s390-virtio-ccw: fix loadparm property getter") > Fixes: Coverity CID 1431058 > Reported-by: Peter Maydell > Signed-off-by: Halil Pasic > --- > hw/s390x/s390-virtio-ccw.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c > index 403d30e13b..8b7bac0392 100644 > --- a/hw/s390x/s390-virtio-ccw.c > +++ b/hw/s390x/s390-virtio-ccw.c > @@ -704,8 +704,8 @@ static char *machine_get_loadparm(Object *obj, Error **errp) > char *loadparm_str; > > /* make a NUL-terminated string */ > - loadparm_str = g_memdup(ms->loadparm, sizeof(ms->loadparm) + 1); > - loadparm_str[sizeof(ms->loadparm)] = 0; > + loadparm_str = g_malloc0(sizeof(ms->loadparm) + 1); > + memcpy(loadparm_str, ms->loadparm, sizeof(ms->loadparm)); I feel like g_strndup(ms->loadparm, sizeof(ms->loadparm)) is what should have been used here. It copies N characters, but allocates N+1 adding a trailing NUL which are the semantic we wanted here. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|