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Re: [Qemu-devel] [PATCH v3 3/5] hw/acpi: Use QEMU_NONSTRING for non NUL-
From: |
Andrew Jones |
Subject: |
Re: [Qemu-devel] [PATCH v3 3/5] hw/acpi: Use QEMU_NONSTRING for non NUL-terminated arrays |
Date: |
Wed, 19 Dec 2018 11:10:34 +0100 |
User-agent: |
NeoMutt/20180716 |
On Tue, Dec 18, 2018 at 06:51:20PM +0100, Philippe Mathieu-Daudé wrote:
> GCC 8 added a -Wstringop-truncation warning:
>
> The -Wstringop-truncation warning added in GCC 8.0 via r254630 for
> bug 81117 is specifically intended to highlight likely unintended
> uses of the strncpy function that truncate the terminating NUL
> character from the source string.
>
> This new warning leads to compilation failures:
>
> CC hw/acpi/core.o
> In function 'acpi_table_install', inlined from 'acpi_table_add' at
> qemu/hw/acpi/core.c:296:5:
> qemu/hw/acpi/core.c:184:9: error: 'strncpy' specified bound 4 equals
> destination size [-Werror=stringop-truncation]
> strncpy(ext_hdr->sig, hdrs->sig, sizeof ext_hdr->sig);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> make: *** [qemu/rules.mak:69: hw/acpi/core.o] Error 1
>
> Use the QEMU_NONSTRING attribute, since ACPI tables don't require the
> strings to be NUL-terminated.
Aren't we always starting with zero-initialized structures in ACPI code?
If so, then we should be able to change the strncpy's to memcpy's.
Thanks,
drew
>
> Suggested-by: Michael S. Tsirkin <address@hidden>
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
> hw/acpi/core.c | 8 ++++----
> include/hw/acpi/acpi-defs.h | 8 ++++----
> 2 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/hw/acpi/core.c b/hw/acpi/core.c
> index aafdc61648..f60f750c3d 100644
> --- a/hw/acpi/core.c
> +++ b/hw/acpi/core.c
> @@ -35,14 +35,14 @@
> struct acpi_table_header {
> uint16_t _length; /* our length, not actual part of the hdr */
> /* allows easier parsing for fw_cfg clients */
> - char sig[4]; /* ACPI signature (4 ASCII characters) */
> + char sig[4] QEMU_NONSTRING; /* ACPI signature (4 ASCII characters) */
> uint32_t length; /* Length of table, in bytes, including header
> */
> uint8_t revision; /* ACPI Specification minor version # */
> uint8_t checksum; /* To make sum of entire table == 0 */
> - char oem_id[6]; /* OEM identification */
> - char oem_table_id[8]; /* OEM table identification */
> + char oem_id[6] QEMU_NONSTRING; /* OEM identification */
> + char oem_table_id[8] QEMU_NONSTRING; /* OEM table identification */
> uint32_t oem_revision; /* OEM revision number */
> - char asl_compiler_id[4]; /* ASL compiler vendor ID */
> + char asl_compiler_id[4] QEMU_NONSTRING; /* ASL compiler vendor ID */
> uint32_t asl_compiler_revision; /* ASL compiler revision number */
> } QEMU_PACKED;
>
> diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
> index af8e023968..3bf0bec8ba 100644
> --- a/include/hw/acpi/acpi-defs.h
> +++ b/include/hw/acpi/acpi-defs.h
> @@ -43,7 +43,7 @@ enum {
> struct AcpiRsdpDescriptor { /* Root System Descriptor Pointer */
> uint64_t signature; /* ACPI signature, contains "RSD PTR "
> */
> uint8_t checksum; /* To make sum of struct == 0 */
> - uint8_t oem_id [6]; /* OEM identification */
> + uint8_t oem_id [6] QEMU_NONSTRING; /* OEM identification */
> uint8_t revision; /* Must be 0 for 1.0, 2 for 2.0 */
> uint32_t rsdt_physical_address; /* 32-bit physical address of RSDT */
> uint32_t length; /* XSDT Length in bytes including hdr */
> @@ -62,10 +62,10 @@ typedef struct AcpiRsdpDescriptor AcpiRsdpDescriptor;
> uint32_t length; /* Length of table, in bytes, including
> header */ \
> uint8_t revision; /* ACPI Specification minor version #
> */ \
> uint8_t checksum; /* To make sum of entire table == 0 */ \
> - uint8_t oem_id [6]; /* OEM identification */ \
> - uint8_t oem_table_id [8]; /* OEM table identification */ \
> + uint8_t oem_id [6] QEMU_NONSTRING; /* OEM identification */ \
> + uint8_t oem_table_id [8] QEMU_NONSTRING; /* OEM table identification */
> \
> uint32_t oem_revision; /* OEM revision number */ \
> - uint8_t asl_compiler_id [4]; /* ASL compiler vendor ID */ \
> + uint8_t asl_compiler_id [4] QEMU_NONSTRING; /* ASL compiler vendor ID
> */ \
> uint32_t asl_compiler_revision; /* ASL compiler revision number */
>
>
> --
> 2.17.2
>
>
- Re: [Qemu-devel] [PATCH v3 1/5] qemu/compiler: Define QEMU_NONSTRING, (continued)
[Qemu-devel] [PATCH v3 4/5] migration: Use QEMU_NONSTRING for non NUL-terminated arrays, Philippe Mathieu-Daudé, 2018/12/18
[Qemu-devel] [PATCH v3 5/5] migration: Use strnlen() for fixed-size string, Philippe Mathieu-Daudé, 2018/12/18
Re: [Qemu-devel] [PATCH v3 0/5] Fix strncpy() warnings for GCC8 new -Wstringop-truncation, Philippe Mathieu-Daudé, 2018/12/18
Re: [Qemu-devel] [PATCH v3 0/5] Fix strncpy() warnings for GCC8 new -Wstringop-truncation, Michael S. Tsirkin, 2018/12/18