linux-kernel - [PATCH] PCI: fix memory leak in reset_method

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Message-ID: <20241001231147.3583649-1-tkjos@google.com>
Date: Tue,  1 Oct 2024 23:11:47 +0000
From: Todd Kjos <tkjos@...gle.com>
To: kernel-team@...roid.com, bhelgaas@...gle.com, linux-pci@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Cc: Todd Kjos <tkjos@...gle.com>
Subject: [PATCH] PCI: fix memory leak in reset_method_store()

In reset_method_store(), a string is allocated via kstrndup()
and assigned to the local "options". options is then used
in with strsep() to find spaces:

  while ((name = strsep(&options, " ")) != NULL) {

If there are no remaining spaces, then options is set to NULL
by strsep(), so the subsequent kfree(options) doesn't free the
memory allocated via kstrndup().

Fix by using a separate tmp_options to iterate with
strsep() so options is preserved.

Fixes: d88f521da3ef ("PCI: Allow userspace to query and set device reset mechanism")
Signed-off-by: Todd Kjos <tkjos@...gle.com>
---
 drivers/pci/pci.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 7d85c04fbba2..0e6562ff3dcf 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5244,7 +5244,7 @@ static ssize_t reset_method_store(struct device *dev,
 				  const char *buf, size_t count)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
-	char *options, *name;
+	char *options, *tmp_options, *name;
 	int m, n;
 	u8 reset_methods[PCI_NUM_RESET_METHODS] = { 0 };
 
@@ -5264,7 +5264,8 @@ static ssize_t reset_method_store(struct device *dev,
 		return -ENOMEM;
 
 	n = 0;
-	while ((name = strsep(&options, " ")) != NULL) {
+	tmp_options = options;
+	while ((name = strsep(&tmp_options, " ")) != NULL) {
 		if (sysfs_streq(name, ""))
 			continue;
 
-- 
2.46.1.824.gd892dcdcdd-goog