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Wed, 1 Sep 2021 14:59:49 +0000 (GMT) From: Fabiano Rosas To: Alexey Kardashevskiy , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots In-Reply-To: <20210901084512.1658628-1-aik@ozlabs.ru> References: <20210901084512.1658628-1-aik@ozlabs.ru> Date: Wed, 01 Sep 2021 11:59:47 -0300 Message-ID: <87fsuouysc.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 9DQBmeqPLuaSHabJAhppr2AOjPjnuUJ6 X-Proofpoint-ORIG-GUID: 9DQBmeqPLuaSHabJAhppr2AOjPjnuUJ6 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.790 definitions=2021-09-01_04:2021-09-01, 2021-09-01 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 suspectscore=0 mlxscore=0 phishscore=0 spamscore=0 impostorscore=0 bulkscore=0 malwarescore=0 mlxlogscore=999 adultscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2109010085 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexey Kardashevskiy , kvm-ppc@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Alexey Kardashevskiy writes: > The userspace can trigger "vmalloc size %lu allocation failure: exceeds > total pages" via the KVM_SET_USER_MEMORY_REGION ioctl. > > This silences the warning by checking the limit before calling vzalloc() > and returns ENOMEM if failed. > > This does not call underlying valloc helpers as __vmalloc_node() is only > exported when CONFIG_TEST_VMALLOC_MODULE and __vmalloc_node_range() is not > exported at all. > > Spotted by syzkaller. > > Signed-off-by: Alexey Kardashevskiy > --- > arch/powerpc/kvm/book3s_hv.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 474c0cfde384..a59f1cccbcf9 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -4830,8 +4830,12 @@ static int kvmppc_core_prepare_memory_region_hv(struct kvm *kvm, > unsigned long npages = mem->memory_size >> PAGE_SHIFT; > > if (change == KVM_MR_CREATE) { > - slot->arch.rmap = vzalloc(array_size(npages, > - sizeof(*slot->arch.rmap))); > + unsigned long cb = array_size(npages, sizeof(*slot->arch.rmap)); What does cb mean? > + > + if ((cb >> PAGE_SHIFT) > totalram_pages()) > + return -ENOMEM; > + > + slot->arch.rmap = vzalloc(cb); > if (!slot->arch.rmap) > return -ENOMEM; > }