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[34.38.181.8]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-65db6dd6ca8sm6202887d50.4.2026.05.13.06.53.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 May 2026 06:53:33 -0700 (PDT) Date: Wed, 13 May 2026 13:53:24 +0000 From: Mostafa Saleh To: Sebastian Ene Cc: catalin.marinas@arm.com, maz@kernel.org, oupton@kernel.org, sudeep.holla@kernel.org, will@kernel.org, joey.gouly@arm.com, korneld@google.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com, mrigendra.chaubey@gmail.com, perlarsen@google.com, suzuki.poulose@arm.com, vdonnefort@google.com, yuzenghui@huawei.com Subject: Re: [PATCH v3 2/2] KVM: arm64: Validate the offset to the mem access descriptor Message-ID: References: <20260512124442.1899107-1-sebastianene@google.com> <20260512124442.1899107-3-sebastianene@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260512124442.1899107-3-sebastianene@google.com> On Tue, May 12, 2026 at 12:44:42PM +0000, Sebastian Ene wrote: > Prevent the pKVM hypervisor from making assumptions that the > endpoint memory access descriptor (EMAD) comes right after the > FF-A memory region header. > Prior to FF-A version 1.1 the header of the memory region > didn't contain an offset to the endpoint memory access descriptor. > The layout of a memory transaction looks like this from 1.1 onward: > Type | Field name | Offset > [ Header | ffa_mem_region | 0 > EMAD 1 | ffa_mem_region_attributes) | ffa_mem_region.ep_mem_offset > ] > Verify that the offset to the first endpoint memory access descriptor > is within the mailbox buffer bounds. > > Signed-off-by: Sebastian Ene Reviewed-by: Mostafa Saleh Thanks, Mostafa > --- > arch/arm64/kvm/hyp/nvhe/ffa.c | 24 ++++++++++++++++++------ > 1 file changed, 18 insertions(+), 6 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c > index 1af722771178..34927bc1239b 100644 > --- a/arch/arm64/kvm/hyp/nvhe/ffa.c > +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c > @@ -479,7 +479,7 @@ static void __do_ffa_mem_xfer(const u64 func_id, > struct ffa_mem_region_attributes *ep_mem_access; > struct ffa_composite_mem_region *reg; > struct ffa_mem_region *buf; > - u32 offset, nr_ranges, checked_offset; > + u32 offset, nr_ranges, checked_offset, em_mem_access_off; > int ret = 0; > > if (addr_mbz || npages_mbz || fraglen > len || > @@ -508,8 +508,14 @@ static void __do_ffa_mem_xfer(const u64 func_id, > buf = hyp_buffers.tx; > memcpy(buf, host_buffers.tx, fraglen); > > - ep_mem_access = (void *)buf + > - ffa_mem_desc_offset(buf, 0, hyp_ffa_version); > + em_mem_access_off = ffa_mem_desc_offset(buf, 0, hyp_ffa_version); > + if (em_mem_access_off > > + KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE - sizeof(struct ffa_mem_region_attributes)) { > + ret = FFA_RET_INVALID_PARAMETERS; > + goto out_unlock; > + } > + > + ep_mem_access = (void *)buf + em_mem_access_off; > offset = ep_mem_access->composite_off; > if (!offset || buf->ep_count != 1 || buf->sender_id != HOST_FFA_ID) { > ret = FFA_RET_INVALID_PARAMETERS; > @@ -576,7 +582,7 @@ static void do_ffa_mem_reclaim(struct arm_smccc_1_2_regs *res, > DECLARE_REG(u32, flags, ctxt, 3); > struct ffa_mem_region_attributes *ep_mem_access; > struct ffa_composite_mem_region *reg; > - u32 offset, len, fraglen, fragoff; > + u32 offset, len, fraglen, fragoff, em_mem_access_off; > struct ffa_mem_region *buf; > int ret = 0; > u64 handle; > @@ -599,8 +605,14 @@ static void do_ffa_mem_reclaim(struct arm_smccc_1_2_regs *res, > len = res->a1; > fraglen = res->a2; > > - ep_mem_access = (void *)buf + > - ffa_mem_desc_offset(buf, 0, hyp_ffa_version); > + em_mem_access_off = ffa_mem_desc_offset(buf, 0, hyp_ffa_version); > + if (em_mem_access_off > > + KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE - sizeof(struct ffa_mem_region_attributes)) { > + ret = FFA_RET_INVALID_PARAMETERS; > + goto out_unlock; > + } > + > + ep_mem_access = (void *)buf + em_mem_access_off; > offset = ep_mem_access->composite_off; > /* > * We can trust the SPMD to get this right, but let's at least > -- > 2.54.0.563.g4f69b47b94-goog >