Re: [PATCH] PCI/AER: potential dereference of null pointer
flat view
From: Bjorn Helgaas <helgaas@kernel.org>
Date: 2021-12-11 17:54:58
Also in:
linux-pci, lkml
[+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:quoted hunk ↗ jump to hunk
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 <redacted> --- 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