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

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Message-ID: <ea7cd581-d6cd-4b0d-986c-d0b43b613858@csgroup.eu>
Date: Mon, 29 Sep 2025 19:01:43 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Breno Leitao <leitao@...ian.org>,
 Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
 Oliver O'Halloran <oohall@...il.com>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.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()



Le 29/09/2025 à 11:15, Breno Leitao a écrit :
> 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://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fr%2F20250804-aer_crash_2-v1-1-fd06562c18a4%40debian.org&data=05%7C02%7Cchristophe.leroy2%40cs-soprasteria.com%7Cf48f0ae03ec542e13e5408ddff38d9d9%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638947341818450358%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=ZzJDmrmyDpWh4JZQQzKFZVf%2BeYucLdNOr5L6tgytNPE%3D&reserved=0
> ---
>   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;
> +

This is a static function, it cannot be called from outside aer.c . Why 
do you need such a check ?

I a check was to be made it should be in pci_aer_init() and in fact if 
kmalloc fails then all the probe should be made to fail.

>   	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>
> 
>