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Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , tabba@google.com, Michael Roth , mhocko@suse.com, wei.w.wang@intel.com Subject: Re: [PATCH v10 9/9] KVM: Enable and expose KVM_MEM_PRIVATE Message-ID: <20230106041346.GA2288017@chaop.bj.intel.com> Reply-To: Chao Peng References: <20221202061347.1070246-1-chao.p.peng@linux.intel.com> <20221202061347.1070246-10-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: AF7DD4000A X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: i15641fjeqn5o1kircwobih3rk88t7n1 X-HE-Tag: 1672978691-362386 X-HE-Meta: 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 HTnFWxuY PDF48Lzl7fCynUncuqRxz5IW0aQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jan 05, 2023 at 12:38:30PM -0800, Vishal Annapurve wrote: > On Thu, Dec 1, 2022 at 10:20 PM Chao Peng wrote: > > > > +#ifdef CONFIG_HAVE_KVM_RESTRICTED_MEM > > +static bool restrictedmem_range_is_valid(struct kvm_memory_slot *slot, > > + pgoff_t start, pgoff_t end, > > + gfn_t *gfn_start, gfn_t *gfn_end) > > +{ > > + unsigned long base_pgoff = slot->restricted_offset >> PAGE_SHIFT; > > + > > + if (start > base_pgoff) > > + *gfn_start = slot->base_gfn + start - base_pgoff; > > There should be a check for overflow here in case start is a very big > value. Additional check can look like: > if (start >= base_pgoff + slot->npages) > return false; > > > + else > > + *gfn_start = slot->base_gfn; > > + > > + if (end < base_pgoff + slot->npages) > > + *gfn_end = slot->base_gfn + end - base_pgoff; > > If "end" is smaller than base_pgoff, this can cause overflow and > return the range as valid. There should be additional check: > if (end < base_pgoff) > return false; Thanks! Both are good catches. The improved code: static bool restrictedmem_range_is_valid(struct kvm_memory_slot *slot, pgoff_t start, pgoff_t end, gfn_t *gfn_start, gfn_t *gfn_end) { unsigned long base_pgoff = slot->restricted_offset >> PAGE_SHIFT; if (start >= base_pgoff + slot->npages) return false; else if (start <= base_pgoff) *gfn_start = slot->base_gfn; else *gfn_start = start - base_pgoff + slot->base_gfn; if (end <= base_pgoff) return false; else if (end >= base_pgoff + slot->npages) *gfn_end = slot->base_gfn + slot->npages; else *gfn_end = end - base_pgoff + slot->base_gfn; if (*gfn_start >= *gfn_end) return false; return true; } Thanks, Chao > > > > + else > > + *gfn_end = slot->base_gfn + slot->npages; > > + > > + if (*gfn_start >= *gfn_end) > > + return false; > > + > > + return true; > > +} > > +