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[146.148.11.143]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4606f2c4240sm6626262f8f.27.2026.06.12.08.20.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jun 2026 08:20:34 -0700 (PDT) Date: Fri, 12 Jun 2026 15:20:30 +0000 From: Sebastian Ene To: Mostafa Saleh Cc: op-tee@lists.trustedfirmware.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, catalin.marinas@arm.com, jens.wiklander@linaro.org, sumit.garg@kernel.org, vdonnefort@google.com, sudeep.holla@kernel.org Subject: Re: [PATCH v6 5/6] KVM: arm64: Validate the offset to the mem access descriptor Message-ID: References: <20260527150236.1978655-1-smostafa@google.com> <20260527150236.1978655-6-smostafa@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260527150236.1978655-6-smostafa@google.com> On Wed, May 27, 2026 at 03:02:35PM +0000, Mostafa Saleh wrote: > From: Sebastian Ene > > 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. > > Also, fix one hardcoded sizeof(struct ffa_mem_region_attributes) that > should be replaced ffa_emad_size_get() for compatibility with FFA v1.0. > > [@Mostafa, Add missing call to ffa_rx_release() and use fraglen > as the max buffer size as it is the only intialised part] > > Fixes: 42fb33dde42b ("KVM: arm64: Use FF-A 1.1 with pKVM") > Signed-off-by: Sebastian Ene > Signed-off-by: Mostafa Saleh > --- > arch/arm64/kvm/hyp/nvhe/ffa.c | 25 ++++++++++++++++++------- > 1 file changed, 18 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c > index b6cf9ad82e12..a12e01883314 100644 > --- a/arch/arm64/kvm/hyp/nvhe/ffa.c > +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c > @@ -476,10 +476,10 @@ static void __do_ffa_mem_xfer(const u64 func_id, > DECLARE_REG(u32, fraglen, ctxt, 2); > DECLARE_REG(u64, addr_mbz, ctxt, 3); > DECLARE_REG(u32, npages_mbz, ctxt, 4); > + u32 offset, nr_ranges, checked_offset, em_mem_access_off; > 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; > int ret = 0; > > if (addr_mbz || npages_mbz || fraglen > len || > @@ -489,7 +489,7 @@ static void __do_ffa_mem_xfer(const u64 func_id, > } > Hi Mostafa, > if (fraglen < sizeof(struct ffa_mem_region) + > - sizeof(struct ffa_mem_region_attributes)) { > + ffa_emad_size_get(hyp_ffa_version)) { > ret = FFA_RET_INVALID_PARAMETERS; > goto out; > } Here sashiko complains about a compatibility break with v1.0 even though it is not from this change. This is because the size of sizeof(struct ffa_mem_region) was 36 bytes in v1.0 and now it is 48. This check can cause "perfectly valid v1.0 memory transfers to be rejected" (from sashiko). Other than that this looks good. I will spin a new version of this series. > @@ -508,8 +508,13 @@ 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 ((u64)em_mem_access_off + ffa_emad_size_get(hyp_ffa_version) > fraglen) { > + 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; > @@ -574,9 +579,9 @@ static void do_ffa_mem_reclaim(struct arm_smccc_1_2_regs *res, > DECLARE_REG(u32, handle_lo, ctxt, 1); > DECLARE_REG(u32, handle_hi, ctxt, 2); > DECLARE_REG(u32, flags, ctxt, 3); > + u32 offset, len, fraglen, fragoff, em_mem_access_off; > struct ffa_mem_region_attributes *ep_mem_access; > struct ffa_composite_mem_region *reg; > - u32 offset, len, fraglen, fragoff; > struct ffa_mem_region *buf; > int ret = 0; > u64 handle; > @@ -599,8 +604,14 @@ 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 ((u64)em_mem_access_off + ffa_emad_size_get(hyp_ffa_version) > fraglen) { > + ret = FFA_RET_INVALID_PARAMETERS; > + ffa_rx_release(res); > + 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 > -- > 2.54.0.746.g67dd491aae-goog > Thanks, Sebastian