linux-kernel - [PATCH] PCI/sysfs: Fix double free in error path

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Date:   Fri,  7 Oct 2022 08:56:18 +0200
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     linux-pci@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Sascha Hauer <s.hauer@...gutronix.de>, stable@...r.kernel.org
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 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@...gutronix.de>
Cc: <stable@...r.kernel.org>
---
 drivers/pci/pci-sysfs.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

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