Re: [Qemu-devel] [PATCH] hw/acpi/nvdimm: Don't take address of fields in packed structs

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 16/10/2018 19:52, Peter Maydell wrote:
> Taking the address of a field in a packed struct is a bad idea, because
> it might not be actually aligned enough for that pointer type (and
> thus cause a crash on dereference on some host architectures). Newer
> versions of clang warn about this. Avoid the bug by not using the
> "modify in place" byte swapping functions.
> 
> Patch produced with scripts/coccinelle/inplace-byteswaps.cocci.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> ---
> Automatically generated patch, tested with "make check" only.
> 
>  hw/acpi/nvdimm.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> index 27eeb6609f5..e53b2cb6819 100644
> --- a/hw/acpi/nvdimm.c
> +++ b/hw/acpi/nvdimm.c
> @@ -581,7 +581,7 @@ static void nvdimm_dsm_func_read_fit(AcpiNVDIMMState *state, NvdimmDsmIn *in,
>      int size;
>  
>      read_fit = (NvdimmFuncReadFITIn *)in->arg3;
> -    le32_to_cpus(&read_fit->offset);
> +    read_fit->offset = le32_to_cpu(read_fit->offset);
>  
>      fit = fit_buf->fit;
>  
> @@ -742,8 +742,8 @@ static void nvdimm_dsm_get_label_data(NVDIMMDevice *nvdimm, NvdimmDsmIn *in,
>      int size;
>  
>      get_label_data = (NvdimmFuncGetLabelDataIn *)in->arg3;
> -    le32_to_cpus(&get_label_data->offset);
> -    le32_to_cpus(&get_label_data->length);
> +    get_label_data->offset = le32_to_cpu(get_label_data->offset);
> +    get_label_data->length = le32_to_cpu(get_label_data->length);
>  
>      nvdimm_debug("Read Label Data: offset %#x length %#x.\n",
>                   get_label_data->offset, get_label_data->length);
> @@ -781,8 +781,8 @@ static void nvdimm_dsm_set_label_data(NVDIMMDevice *nvdimm, NvdimmDsmIn *in,
>  
>      set_label_data = (NvdimmFuncSetLabelDataIn *)in->arg3;
>  
> -    le32_to_cpus(&set_label_data->offset);
> -    le32_to_cpus(&set_label_data->length);
> +    set_label_data->offset = le32_to_cpu(set_label_data->offset);
> +    set_label_data->length = le32_to_cpu(set_label_data->length);
>  
>      nvdimm_debug("Write Label Data: offset %#x length %#x.\n",
>                   set_label_data->offset, set_label_data->length);
> @@ -877,9 +877,9 @@ nvdimm_dsm_write(void *opaque, hwaddr addr, uint64_t val, unsigned size)
>      in = g_new(NvdimmDsmIn, 1);
>      cpu_physical_memory_read(dsm_mem_addr, in, sizeof(*in));
>  
> -    le32_to_cpus(&in->revision);
> -    le32_to_cpus(&in->function);
> -    le32_to_cpus(&in->handle);
> +    in->revision = le32_to_cpu(in->revision);
> +    in->function = le32_to_cpu(in->function);
> +    in->handle = le32_to_cpu(in->handle);
>  
>      nvdimm_debug("Revision %#x Handler %#x Function %#x.\n", in->revision,
>                   in->handle, in->function);
>