RE: [PATCH] nfit: Fix nfit_intel_shutdown_status() command submission

[Dexuan Cui]

> From: Dan Williams <dan.j.williams@xxxxxxxxx>
> Sent: Monday, January 28, 2019 9:22 PM
> To: linux-nvdimm@xxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx; Dexuan Cui <decui@xxxxxxxxxxxxx>;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH] nfit: Fix nfit_intel_shutdown_status() command submission
> 
> The implementation is broken in all the ways the unit test did not touch:
> 
> 1/ The local definition of in_buf and in_obj violated C99 initializer
>    expectations for zeroing. By only initializing 2 out of the three
>    struct members the compiler was free to zero-initialize the remaining
>    entry even though the aliased location in the union was initialized.
> 
> 2/ The implementation made assumptions about the state of the 'smart'
>    payload after command execution that are satisfied by
>    acpi_nfit_ctl(), but not acpi_evaluate_dsm().
> 
> 3/ populate_shutdown_status() is skipped on Intel NVDIMMs due to the early
>    return for skipping the common _LS{I,R,W} enabling.
> 
> 4/ The input length should be zero.
> 
> This breakage was missed due to the unit test implementation only
> testing the case where nfit_intel_shutdown_status() returns a valid
> payload.
> 
> Much of this complexity would be saved if acpi_nfit_ctl() could be used, but
> that currently requires a 'struct nvdimm *' argument and one is not created
> until later in the init process. The health result is needed before the device
> is created because the payload gates whether the nmemX/nfit/dirty_shutdown
> property is visible in sysfs.
> 
> Cc: <stable@xxxxxxxxxxxxxxx>
> Fixes: 0ead11181fe0 ("acpi, nfit: Collect shutdown status")
> Reported-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
>  drivers/acpi/nfit/core.c |   41 ++++++++++++++++++++++++-----------------
>  1 file changed, 24 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index e18ade5d74e9..0a49c57334cc 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -1759,14 +1759,14 @@ static bool acpi_nvdimm_has_method(struct
> acpi_device *adev, char *method)
> 
>  __weak void nfit_intel_shutdown_status(struct nfit_mem *nfit_mem)
>  {
> +	struct device *dev = &nfit_mem->adev->dev;
>  	struct nd_intel_smart smart = { 0 };
>  	union acpi_object in_buf = {
> -		.type = ACPI_TYPE_BUFFER,
> -		.buffer.pointer = (char *) &smart,
> -		.buffer.length = sizeof(smart),
> +		.buffer.type = ACPI_TYPE_BUFFER,
> +		.buffer.length = 0,
>  	};
>  	union acpi_object in_obj = {
> -		.type = ACPI_TYPE_PACKAGE,
> +		.package.type = ACPI_TYPE_PACKAGE,
>  		.package.count = 1,
>  		.package.elements = &in_buf,
>  	};
> @@ -1781,8 +1781,15 @@ __weak void nfit_intel_shutdown_status(struct
> nfit_mem *nfit_mem)
>  		return;
> 
>  	out_obj = acpi_evaluate_dsm(handle, guid, revid, func, &in_obj);
> -	if (!out_obj)
> +	if (!out_obj || out_obj->type != ACPI_TYPE_BUFFER
> +			|| out_obj->buffer.length < sizeof(smart)) {
> +		dev_dbg(dev->parent, "%s: failed to retrieve initial health\n",
> +				dev_name(dev));
> +		ACPI_FREE(out_obj);
>  		return;
> +	}
> +	memcpy(&smart, out_obj->buffer.pointer, sizeof(smart));
> +	ACPI_FREE(out_obj);
> 
>  	if (smart.flags & ND_INTEL_SMART_SHUTDOWN_VALID) {
>  		if (smart.shutdown_state)
> @@ -1793,7 +1800,6 @@ __weak void nfit_intel_shutdown_status(struct
> nfit_mem *nfit_mem)
>  		set_bit(NFIT_MEM_DIRTY_COUNT, &nfit_mem->flags);
>  		nfit_mem->dirty_shutdown = smart.shutdown_count;
>  	}
> -	ACPI_FREE(out_obj);
>  }
> 
>  static void populate_shutdown_status(struct nfit_mem *nfit_mem)
> @@ -1915,18 +1921,19 @@ static int acpi_nfit_add_dimm(struct
> acpi_nfit_desc *acpi_desc,
>  		| 1 << ND_CMD_SET_CONFIG_DATA;
>  	if (family == NVDIMM_FAMILY_INTEL
>  			&& (dsm_mask & label_mask) == label_mask)
> -		return 0;
> -
> -	if (acpi_nvdimm_has_method(adev_dimm, "_LSI")
> -			&& acpi_nvdimm_has_method(adev_dimm, "_LSR")) {
> -		dev_dbg(dev, "%s: has _LSR\n", dev_name(&adev_dimm->dev));
> -		set_bit(NFIT_MEM_LSR, &nfit_mem->flags);
> -	}
> +		/* skip _LS{I,R,W} enabling */;
> +	else {
> +		if (acpi_nvdimm_has_method(adev_dimm, "_LSI")
> +				&& acpi_nvdimm_has_method(adev_dimm, "_LSR")) {
> +			dev_dbg(dev, "%s: has _LSR\n", dev_name(&adev_dimm->dev));
> +			set_bit(NFIT_MEM_LSR, &nfit_mem->flags);
> +		}
> 
> -	if (test_bit(NFIT_MEM_LSR, &nfit_mem->flags)
> -			&& acpi_nvdimm_has_method(adev_dimm, "_LSW")) {
> -		dev_dbg(dev, "%s: has _LSW\n", dev_name(&adev_dimm->dev));
> -		set_bit(NFIT_MEM_LSW, &nfit_mem->flags);
> +		if (test_bit(NFIT_MEM_LSR, &nfit_mem->flags)
> +				&& acpi_nvdimm_has_method(adev_dimm, "_LSW")) {
> +			dev_dbg(dev, "%s: has _LSW\n", dev_name(&adev_dimm->dev));
> +			set_bit(NFIT_MEM_LSW, &nfit_mem->flags);
> +		}
>  	}
> 
>  	populate_shutdown_status(nfit_mem);

Reviewed-by: Dexuan Cui <decui@xxxxxxxxxxxxx>

Thanks for the fix, Dan!

-- Dexuan