Re: [PATCH -next] scsi: hisi_sas: drop free_irq of devm_request_irq allocated irq

From: John Garry
Date: Wed May 19 2021 - 07:20:27 EST


On 19/05/2021 04:36, Yang Yingliang wrote:

On 2021/5/18 23:34, John Garry wrote:
On 18/05/2021 14:09, Yang Yingliang wrote:
irq allocated with devm_request_irq should not be freed using
free_irq, because doing so causes a dangling pointer, and a
subsequent double free.

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
---
  drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
index 499c770d405c..684f762bcfb3 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
@@ -4811,9 +4811,9 @@ hisi_sas_v3_destroy_irqs(struct pci_dev *pdev, struct hisi_hba *hisi_hba)
  {
      int i;
  -    free_irq(pci_irq_vector(pdev, 1), hisi_hba);
-    free_irq(pci_irq_vector(pdev, 2), hisi_hba);
-    free_irq(pci_irq_vector(pdev, 11), hisi_hba);
+    devm_free_irq(&pdev->dev, pci_irq_vector(pdev, 1), hisi_hba);
+    devm_free_irq(&pdev->dev, pci_irq_vector(pdev, 2), hisi_hba);
+    devm_free_irq(&pdev->dev, pci_irq_vector(pdev, 11), hisi_hba);
      for (i = 0; i < hisi_hba->cq_nvecs; i++) {
          struct hisi_sas_cq *cq = &hisi_hba->cq[i];
          int nr = hisi_sas_intr_conv ? 16 : 16 + i;


Does the free_irq(pci_irq_vector(pdev, nr, cq)) call also need to change (not shown)?
Yes, I missed that, it should be changed too.

So I think that we need this addition:
devm_free_irq(&pdev->dev, pci_irq_vector(pdev, nr), cq);


Having said that, why have these at all if we use devm_request_irq()? devm_irq_release() calls free_irq().
I keep the original logic here, only avoid double free.

Kasan doesn't complain. Anyway, I think we can't rely on device-managed method (for calling free_irq()) as it conflicts with pci free vectors call. I thought that someone was developed a device-managed version of that (pci_alloc_irq_vectors()).

Anyway, please proceed with your change, but with the suggested addition.

Thanks