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[146.148.11.143]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490e2d09a85sm146043915e9.14.2026.06.12.06.48.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jun 2026 06:48:31 -0700 (PDT) Date: Fri, 12 Jun 2026 13:48:27 +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 3/6] firmware: arm_ffa: Fix Endpoint Memory Access Descriptor offset calculation Message-ID: References: <20260527150236.1978655-1-smostafa@google.com> <20260527150236.1978655-4-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: <20260527150236.1978655-4-smostafa@google.com> On Wed, May 27, 2026 at 03:02:33PM +0000, Mostafa Saleh wrote: Hi Mostafa, > From: Sebastian Ene > > Use the descriptor's `ep_mem_offset` to calculate the start of the endpoint > memory access array and to comply with the FF-A spec instead of defaulting > to `sizeof(struct ffa_mem_region)`. > This requires moving `ffa_mem_region_additional_setup()` earlier in the setup > flow. > Also, add sanity checks to ensure the calculated descriptor offsets do not > exceed `max_fragsize`. > [@Mostafa Harden error checking] > > Fixes: 113580530ee7 ("firmware: arm_ffa: Update memory descriptor to support v1.1 format") > Signed-off-by: Sebastian Ene > Reviewed-by: Sudeep Holla > Signed-off-by: Mostafa Saleh > --- > drivers/firmware/arm_ffa/driver.c | 16 +++++++++++----- > include/linux/arm_ffa.h | 2 +- > 2 files changed, 12 insertions(+), 6 deletions(-) > > diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c > index 059e2aae7ca0..bed4bd48963f 100644 > --- a/drivers/firmware/arm_ffa/driver.c > +++ b/drivers/firmware/arm_ffa/driver.c > @@ -703,19 +703,26 @@ ffa_setup_and_transmit(u32 func_id, void *buffer, u32 max_fragsize, > struct ffa_composite_mem_region *composite; > struct ffa_mem_region_addr_range *constituents; > struct ffa_mem_region_attributes *ep_mem_access; > - u32 idx, frag_len, length, buf_sz = 0, num_entries = sg_nents(args->sg); > + u32 idx, frag_len, length, buf_sz = 0, num_entries = sg_nents(args->sg), ep_offset; > + u32 emad_size = ffa_emad_size_get(drv_info->version); > > mem_region->tag = args->tag; > mem_region->flags = args->flags; > mem_region->sender_id = drv_info->vm_id; > mem_region->attributes = ffa_memory_attributes_get(func_id); > + > + ffa_mem_region_additional_setup(drv_info->version, mem_region); > composite_offset = ffa_mem_desc_offset(buffer, args->nattrs, > drv_info->version); > + if (composite_offset + sizeof(*composite) > max_fragsize) > + return -ENXIO; > > for (idx = 0; idx < args->nattrs; idx++) { > - ep_mem_access = buffer + > - ffa_mem_desc_offset(buffer, idx, drv_info->version); > - memset(ep_mem_access, 0, ffa_emad_size_get(drv_info->version)); > + ep_offset = ffa_mem_desc_offset(buffer, idx, drv_info->version); > + if (ep_offset + emad_size > max_fragsize) > + return -ENXIO; Looking between v3 (the version that I sent) and this version, you account correctly for the emad_size which depends on the FF-A version (thus the introduced call to ffa_emad_size_get()). I think the only remaining bit here is making sure that we don't overflow in `ep_offset + emad_size`. > + ep_mem_access = buffer + ep_offset; > + memset(ep_mem_access, 0, emad_size); > ep_mem_access->receiver = args->attrs[idx].receiver; > ep_mem_access->attrs = args->attrs[idx].attrs; > ep_mem_access->composite_off = composite_offset; > @@ -725,7 +732,6 @@ ffa_setup_and_transmit(u32 func_id, void *buffer, u32 max_fragsize, > } > mem_region->handle = 0; > mem_region->ep_count = args->nattrs; > - ffa_mem_region_additional_setup(drv_info->version, mem_region); > > composite = buffer + composite_offset; > composite->total_pg_cnt = ffa_get_num_pages_sg(args->sg); > diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h > index 81e603839c4a..62d67dae8b70 100644 > --- a/include/linux/arm_ffa.h > +++ b/include/linux/arm_ffa.h > @@ -445,7 +445,7 @@ ffa_mem_desc_offset(struct ffa_mem_region *buf, int count, u32 ffa_version) > if (!FFA_MEM_REGION_HAS_EP_MEM_OFFSET(ffa_version)) > offset += offsetof(struct ffa_mem_region, ep_mem_offset); > else > - offset += sizeof(struct ffa_mem_region); > + offset += buf->ep_mem_offset; > > return offset; > } > -- > 2.54.0.746.g67dd491aae-goog > Thanks, Sebastian