On Fri, Oct 07, 2022 at 08:56:18AM +0200, Sascha Hauer wrote:

When pci_create_attr() fails then pci_remove_resource_files() is called which will iterate over the res_attr[_wc] arrays and frees every non NULL entry. To avoid a double free here we have to set the failed entry to NULL in pci_create_attr() when freeing it.

You might consider applying this alternative version instead which IMO looks a bit better.

Sascha

-------------------------------8<-----------------------------

From fe8e0e6f914c14395c751b7dc165967b12427995 Mon Sep 17 00:00:00 2001 From: Sascha Hauer s.hauer@pengutronix.de Date: Fri, 7 Oct 2022 07:35:35 +0200 Subject: [PATCH] PCI/sysfs: Fix double free in error path

When pci_create_attr() fails then pci_remove_resource_files() is called which will iterate over the res_attr[_wc] arrays and frees every non NULL entry. To avoid a double free here set the array entry only after it's clear we successfully initialized it.

Fixes: b562ec8f74e4 ("PCI: Don't leak memory if sysfs_create_bin_file() fails") Signed-off-by: Sascha Hauer s.hauer@pengutronix.de Cc: stable@vger.kernel.org --- drivers/pci/pci-sysfs.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index fc804e08e3cb5..6dd4050c9f2ed 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -1174,11 +1174,9 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)

sysfs_bin_attr_init(res_attr); if (write_combine) { - pdev->res_attr_wc[num] = res_attr; sprintf(res_attr_name, "resource%d_wc", num); res_attr->mmap = pci_mmap_resource_wc; } else { - pdev->res_attr[num] = res_attr; sprintf(res_attr_name, "resource%d", num); if (pci_resource_flags(pdev, num) & IORESOURCE_IO) { res_attr->read = pci_read_resource_io; @@ -1196,10 +1194,17 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine) res_attr->size = pci_resource_len(pdev, num); res_attr->private = (void *)(unsigned long)num; retval = sysfs_create_bin_file(&pdev->dev.kobj, res_attr); - if (retval) + if (retval) { kfree(res_attr); + return retval; + } + + if (write_combine) + pdev->res_attr_wc[num] = res_attr; + else + pdev->res_attr[num] = res_attr;

- return retval; + return 0; }

/**

Hi Bjorn,

On Fri, Oct 07, 2022 at 08:56:18AM +0200, Sascha Hauer wrote:

When pci_create_attr() fails then pci_remove_resource_files() is called which will iterate over the res_attr[_wc] arrays and frees every non NULL entry. To avoid a double free here we have to set the failed entry to NULL in pci_create_attr() when freeing it.

Fixes: b562ec8f74e4 ("PCI: Don't leak memory if sysfs_create_bin_file() fails") Signed-off-by: Sascha Hauer s.hauer@pengutronix.de Cc: stable@vger.kernel.org

---

drivers/pci/pci-sysfs.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)

Any input to this one? There's this long unfixed race condition described here:

https://patchwork.kernel.org/project/linux-pci/patch/20200716110423.xtfyb3n6...

And this patch at least prevents my system from crashing when this race condition occurs.

Sascha

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index fc804e08e3cb5..a07381d46ddae 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -1196,8 +1196,13 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine) res_attr->size = pci_resource_len(pdev, num); res_attr->private = (void *)(unsigned long)num; retval = sysfs_create_bin_file(&pdev->dev.kobj, res_attr);

• if (retval)

• if (retval) {

• if (write_combine)
  

• 	pdev->res_attr_wc[num] = NULL;
  

• else
  

• 	pdev->res_attr[num] = NULL;
  

  kfree(res_attr);
• }

return retval; } -- 2.30.2