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Mon, 11 Jan 2021 12:58:05 +0000 (UTC) Date: Mon, 11 Jan 2021 07:58:04 -0500 (EST) From: Miroslav Rezanina To: Thomas Huth Message-ID: <1585780817.32405499.1610369884713.JavaMail.zimbra@redhat.com> In-Reply-To: References: <5acb5521-fdd2-e511-9cc3-176086183dd5@redhat.com> <88c2eb01-f8f5-18d5-6513-57322930cc77@redhat.com> <115622555.32388560.1610368920610.JavaMail.zimbra@redhat.com> Subject: Re: [RHEL7 qemu-kvm PATCH 2/3] s390x: Fix vm name copy length MIME-Version: 1.0 X-Originating-IP: [10.40.192.93, 10.4.195.10] Thread-Topic: s390x: Fix vm name copy length Thread-Index: x0b7tkYAwH3VkWLyuGFCJNGF8YrE6w== X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mrezanin@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=216.205.24.124; envelope-from=mrezanin@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.251, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-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: , Cc: qemu-s390x , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" ----- Original Message ----- > From: "Thomas Huth" > To: "Miroslav Rezanina" > Cc: "qemu-s390x" , "Philippe Mathieu-Daud=C3=A9" <= philmd@redhat.com>, qemu-devel@nongnu.org > Sent: Monday, January 11, 2021 1:54:06 PM > Subject: Re: [RHEL7 qemu-kvm PATCH 2/3] s390x: Fix vm name copy length >=20 > On 11/01/2021 13.42, Miroslav Rezanina wrote: > >=20 > >=20 > > ----- Original Message ----- > >> From: "Thomas Huth" > >> To: "Philippe Mathieu-Daud=C3=A9" , mrezanin@redhat= .com, > >> qemu-devel@nongnu.org, "qemu-s390x" > >> > >> Sent: Monday, January 11, 2021 1:24:57 PM > >> Subject: Re: [RHEL7 qemu-kvm PATCH 2/3] s390x: Fix vm name copy length > >> > >> On 11/01/2021 13.10, Philippe Mathieu-Daud=C3=A9 wrote: > >>> Hi Miroslav, > >>> > >>> On 1/11/21 12:30 PM, mrezanin@redhat.com wrote: > >>>> From: Miroslav Rezanina > >>>> > >>>> There are two cases when vm name is copied but closing \0 can be los= t > >>>> in case name is too long (>=3D256 characters). > >>>> > >>>> Updating length to copy so there is space for closing \0. > >>>> > >>>> Signed-off-by: Miroslav Rezanina > >>>> --- > >>>> target/s390x/kvm.c | 2 +- > >>>> target/s390x/misc_helper.c | 4 +++- > >>>> 2 files changed, 4 insertions(+), 2 deletions(-) > >>>> > >>>> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c > >>>> index b8385e6b95..2313b5727e 100644 > >>>> --- a/target/s390x/kvm.c > >>>> +++ b/target/s390x/kvm.c > >>>> @@ -1918,7 +1918,7 @@ static void insert_stsi_3_2_2(S390CPU *cpu, __= u64 > >>>> addr, uint8_t ar) > >>>> */ > >>>> if (qemu_name) { > >>>> strncpy((char *)sysib.ext_names[0], qemu_name, > >>>> - sizeof(sysib.ext_names[0])); > >>>> + sizeof(sysib.ext_names[0]) - 1); > >>>> } else { > >>>> strcpy((char *)sysib.ext_names[0], "KVMguest"); > >>>> } > >>> > >>> What about using strpadcpy() instead? > >> > >> Yes, strpadcpy is the better way here - this field has to be padded wi= th > >> zeroes, so doing "- 1" is wrong here. > >=20 > > Hi Thomas, > >=20 > > as I wrote in reply to Phillipe - the array is memset to zeroes before = the > > if so we > > are sure it's padded with zeroes (in this occurrence, not true for seco= nd > > one). >=20 > Ok, but dropping the last character is still wrong here. The ext_names do > not need to be terminated with a \0 if they have the full length. Oh, they do not have to end with \0??? I did not know it. In that case we probably have to use strpadcpy to get rid of the compiler warning. Mirek >=20 > Thomas >=20 --=20 Miroslav Rezanina Software Engineer - Virtualization Team Maintainer