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

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Message-ID: <50f6c23f-1f46-4be1-813a-c11f2db3ec4f@gmail.com>
Date: Wed, 6 Aug 2025 09:55:05 +0800
From: Ethan Zhao <etzhao1900@...il.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>,
 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
Subject: Re: [PATCH] PCI/AER: Check for NULL aer_info before ratelimiting in
 pci_print_aer()



On 8/4/2025 5:17 PM, 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.
> 
The enqueue side has lock to protect the ring, but the dequeue side no 
lock held.

The kfifo_get in
static void aer_recover_work_func(struct work_struct *work)
{
...
while (kfifo_get(&aer_recover_ring, &entry)) {
...
}
should be replaced by
kfifo_out_spinlocked()

as
static void aer_recover_work_func(struct work_struct *work)
{
...
while (kfifo_out_spinlocked(&aer_recover_ring, 
&entry,1`,&aer_recover_ring_lock )) {
...
}


Thanks,
Ethan

> Signed-off-by: Breno Leitao <leitao@...ian.org>
> Fixes: a57f2bfb4a5863 ("PCI/AER: Ratelimit correctable and non-fatal error logging")
> ---
>   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 70ac661883672..b5f96fde4dcda 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: 89748acdf226fd1a8775ff6fa2703f8412b286c8
> change-id: 20250801-aer_crash_2-b21cc2ef0d00
> 
> Best regards,
> --
> Breno Leitao <leitao@...ian.org>
> 
>