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

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Message-ID: <z5thnuj2nwzuk7wp7kentekm7zx6v6fh5f6zknerdbld665guo@6uxxl7emi3be>
Date: Thu, 2 Oct 2025 02:10:56 -0700
From: Breno Leitao <leitao@...ian.org>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: 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>, 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 Wed, Oct 01, 2025 at 04:36:57PM -0500, Bjorn Helgaas wrote:
> On Mon, Sep 29, 2025 at 02:15:47AM -0700, 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>
> 
> Thanks, Breno, I applied this to pci/aer for v6.18.  I added a little
> more detail to the commit log because the path where we hit this is a
> bit obscure.  Please take a look and see if it makes sense:

Thanks! That’s exactly what I would have written if I actually knew what
I was doing. :-)