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[3.72.134.22]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-af91a21c076sm976544866b.102.2025.08.05.18.55.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Aug 2025 18:55:07 -0700 (PDT) Message-ID: <50f6c23f-1f46-4be1-813a-c11f2db3ec4f@gmail.com> Date: Wed, 6 Aug 2025 09:55:05 +0800 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] PCI/AER: Check for NULL aer_info before ratelimiting in pci_print_aer() To: Breno Leitao , Mahesh J Salgaonkar , Oliver O'Halloran , Bjorn Helgaas , Kuppuswamy Sathyanarayanan , Jon Pan-Doh Cc: linuxppc-dev@lists.ozlabs.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com References: <20250804-aer_crash_2-v1-1-fd06562c18a4@debian.org> Content-Language: en-US From: Ethan Zhao In-Reply-To: <20250804-aer_crash_2-v1-1-fd06562c18a4@debian.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 > 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 > >