From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34770) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1acwwm-000566-9A for qemu-devel@nongnu.org; Mon, 07 Mar 2016 10:19:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1acwwf-0005Y4-Bg for qemu-devel@nongnu.org; Mon, 07 Mar 2016 10:19:48 -0500 From: Igor Mammedov Date: Mon, 7 Mar 2016 16:19:06 +0100 Message-Id: <1457363948-71300-5-git-send-email-imammedo@redhat.com> In-Reply-To: <1457363948-71300-1-git-send-email-imammedo@redhat.com> References: <1457363948-71300-1-git-send-email-imammedo@redhat.com> Subject: [Qemu-devel] [PATCH 4/6] tpm: apci: cleanup TCPA table initialization List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: peter.maydell@linaro.org, guangrong.xiao@linux.intel.com, ehabkost@redhat.com, mst@redhat.com, qemu-arm@nongnu.org, zhaoshenglong@huawei.com, pbonzini@redhat.com At the time build_tpm_tcpa() is called the tcpalog size is always 0, so log_area_start_address which is actually offset from the start of ACPI_BUILD_TPMLOG_FILE is always 0. More over if tcpalog would be not 0 sized at build_tpm_tcpa() calling time it would make tcpa->log_area_start_address point to ACPI_BUILD_TPMLOG_FILE+log_area_start_address causing guest to write beyound ACPI_BUILD_TPMLOG_FILE which would resulted to memory corruption. As 'TCPA' is allocated 0 filled, there is not point to calculate constant 0 log_area_start_address and set tcpa->log_area_start_address to it since the field should always point to start of ACPI_BUILD_TPMLOG_FILE. Make code easier to read dropping misleading at best offset calculations and making it impossible to silently backfire if tcpalog size becomes non 0 at the time build_tpm_tcpa() is called in future. While at that move tcpalog allocation closer to the code that defines its size. Signed-off-by: Igor Mammedov --- hw/i386/acpi-build.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c index e13f96d..3540815 100644 --- a/hw/i386/acpi-build.c +++ b/hw/i386/acpi-build.c @@ -2310,11 +2310,10 @@ static void build_tpm_tcpa(GArray *table_data, BIOSLinker *linker, GArray *tcpalog) { Acpi20Tcpa *tcpa = acpi_data_push(table_data, sizeof *tcpa); - uint64_t log_area_start_address = acpi_data_len(tcpalog); tcpa->platform_class = cpu_to_le16(TPM_TCPA_ACPI_CLASS_CLIENT); tcpa->log_area_minimum_length = cpu_to_le32(TPM_LOG_AREA_MINIMUM_SIZE); - tcpa->log_area_start_address = cpu_to_le64(log_area_start_address); + acpi_data_push(tcpalog, tcpa->log_area_minimum_length); bios_linker_loader_alloc(linker, ACPI_BUILD_TPMLOG_FILE, tcpalog, 1, false /* high memory */); @@ -2327,8 +2326,6 @@ build_tpm_tcpa(GArray *table_data, BIOSLinker *linker, GArray *tcpalog) build_header(linker, table_data, (void *)tcpa, "TCPA", sizeof(*tcpa), 2, NULL, NULL); - - acpi_data_push(tcpalog, TPM_LOG_AREA_MINIMUM_SIZE); } static void -- 1.8.3.1