linux-kernel - Re: [PATCH v4 3/8] PCI/DPC: Initialize info->id in dpc_process_error()

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Message-ID: <20211021012800.GA2656128@bhelgaas>
Date:   Wed, 20 Oct 2021 20:28:00 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Naveen Naidu <naveennaidu479@...il.com>
Cc:     bhelgaas@...gle.com, ruscur@...sell.cc, oohall@...il.com,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH v4 3/8] PCI/DPC: Initialize info->id in
 dpc_process_error()

On Tue, Oct 05, 2021 at 10:48:10PM +0530, Naveen Naidu wrote:
> In the dpc_process_error() path, info->id isn't initialized before being
> passed to aer_print_error(). In the corresponding AER path, it is
> initialized in aer_isr_one_error().
> 
> The error message shown during Coverity Scan is:
> 
>   Coverity #1461602
>   CID 1461602 (#1 of 1): Uninitialized scalar variable (UNINIT)
>   8. uninit_use_in_call: Using uninitialized value info.id when calling aer_print_error.
> 
> Initialize the "info->id" before passing it to aer_print_error()
> 
> Fixes: 8aefa9b0d910 ("PCI/DPC: Print AER status in DPC event handling")
> Signed-off-by: Naveen Naidu <naveennaidu479@...il.com>
> ---
>  drivers/pci/pcie/dpc.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index c556e7beafe3..df3f3a10f8bc 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -262,14 +262,14 @@ static int dpc_get_aer_uncorrect_severity(struct pci_dev *dev,
>  
>  void dpc_process_error(struct pci_dev *pdev)
>  {
> -	u16 cap = pdev->dpc_cap, status, source, reason, ext_reason;
> +	u16 cap = pdev->dpc_cap, status, reason, ext_reason;
>  	struct aer_err_info info;
>  
>  	pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
> -	pci_read_config_word(pdev, cap + PCI_EXP_DPC_SOURCE_ID, &source);
> +	pci_read_config_word(pdev, cap + PCI_EXP_DPC_SOURCE_ID, &info.id);
>  
>  	pci_info(pdev, "containment event, status:%#06x source:%#06x\n",
> -		 status, source);
> +		 status, info.id);
>  
>  	reason = (status & PCI_EXP_DPC_STATUS_TRIGGER_RSN) >> 1;

Per PCIe r5.0, sec 7.9.15.5, the Source ID is defined only when the
Trigger Reason indicates ERR_NONFATAL or ERR_FATAL.  So I think we
need to extract this reason before reading PCI_EXP_DPC_SOURCE_ID,
e.g.,

  reason = (status & PCI_EXP_DPC_STATUS_TRIGGER_RSN) >> 1;
  if (reason == 1 || reason == 2)
    pci_read_config_word(pdev, cap + PCI_EXP_DPC_SOURCE_ID, &info.id);
  else
    info.id = 0;

>  	ext_reason = (status & PCI_EXP_DPC_STATUS_TRIGGER_RSN_EXT) >> 5;
> -- 
> 2.25.1
> 
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