[+cc Rajat, author of aer_stats:
db89ccbe52c7 ("PCI/AER: Define aer_stats structure for AER capable devices"
81aa5206f9a7 ("PCI/AER: Add sysfs attributes to provide AER stats and breakdown"]
On Thu, Dec 09, 2021 at 05:45:56PM +0800, Jiasheng Jiang wrote:
> he return value of kzalloc() needs to be checked.
> To avoid use of null pointer in case of the failure of alloc.
>
> Fixes: db89ccbe52c7 ("PCI/AER: Define aer_stats structure for AER capable devices")
> Signed-off-by: Jiasheng Jiang <jiasheng@xxxxxxxxxxx>
> ---
> drivers/pci/pcie/aer.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index ec943cee5ecc..d04303edf468 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -376,6 +376,8 @@ void pci_aer_init(struct pci_dev *dev)
> return;
>
> dev->aer_stats = kzalloc(sizeof(struct aer_stats), GFP_KERNEL);
> + if (!dev->aer_stats)
> + return;
Did you actually trip over a null pointer dereference, and if so,
where was it?
I think the intent here was that aer_stats is a non-essential feature,
and if we can't allocate space to keep the statistics, we can still
use the device without the stats.
I *think* all the users of dev->aer_stats check for NULL before
dereferencing it, but if you found a case that doesn't do that, we
should definitely fix it.
In a few cases (aer_stats_dev_attr, aer_stats_rootport_attr), the
check isn't obvious -- it happens in aer_stats_attrs_are_visible().
If aer_stats_attrs_are_visible() finds that aer_stats is NULL, those
sysfs attributes should not be visible, and the corresponding *_show()
functions should never be called.
> /*
> * We save/restore PCI_ERR_UNCOR_MASK, PCI_ERR_UNCOR_SEVER,
> --
> 2.25.1
>
