linux-kernel - Re: [PATCH RESEND] PCI/AER: Check for NULL aer_info before ratelimiting in pci_print

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Message-ID: <7b5c1235-df92-4f18-936c-3d7c0d3a6cb3@linux.intel.com>
Date: Mon, 29 Sep 2025 08:10:03 -0700
From: Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Breno Leitao <leitao@...ian.org>,
 Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
 Oliver O'Halloran <oohall@...il.com>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Jon Pan-Doh <pandoh@...gle.com>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org, kernel-team@...a.com, stable@...r.kernel.org
Subject: Re: [PATCH RESEND] PCI/AER: Check for NULL aer_info before
 ratelimiting in pci_print_aer()


On 9/29/25 2:15 AM, Breno Leitao wrote:
> Similarly to pci_dev_aer_stats_incr(), pci_print_aer() may be called
> when dev->aer_info is NULL. Add a NULL check before proceeding to avoid
> calling aer_ratelimit() with a NULL aer_info pointer, returning 1, which
> does not rate limit, given this is fatal.
>
> This prevents a kernel crash triggered by dereferencing a NULL pointer
> in aer_ratelimit(), ensuring safer handling of PCI devices that lack
> AER info. This change aligns pci_print_aer() with pci_dev_aer_stats_incr()
> which already performs this NULL check.
>
> Cc: stable@...r.kernel.org
> Fixes: a57f2bfb4a5863 ("PCI/AER: Ratelimit correctable and non-fatal error logging")
> Signed-off-by: Breno Leitao <leitao@...ian.org>
> ---
> - This problem is still happening in upstream, and unfortunately no action
>    was done in the previous discussion.
> - Link to previous post:
>    https://lore.kernel.org/r/20250804-aer_crash_2-v1-1-fd06562c18a4@debian.org
> ---

Although we haven't identified the path that triggers this issue, adding this check is harmless.

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>



>   drivers/pci/pcie/aer.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index e286c197d7167..55abc5e17b8b1 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -786,6 +786,9 @@ static void pci_rootport_aer_stats_incr(struct pci_dev *pdev,
>   
>   static int aer_ratelimit(struct pci_dev *dev, unsigned int severity)
>   {
> +	if (!dev->aer_info)
> +		return 1;
> +
>   	switch (severity) {
>   	case AER_NONFATAL:
>   		return __ratelimit(&dev->aer_info->nonfatal_ratelimit);
>
> ---
> base-commit: e5f0a698b34ed76002dc5cff3804a61c80233a7a
> change-id: 20250801-aer_crash_2-b21cc2ef0d00
>
> Best regards,
> --
> Breno Leitao <leitao@...ian.org>
>
-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer