[PATCH 6.1 107/379] platform/x86: wmi: Fix opening of char device

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Armin Wolf <W_Armin@xxxxxx>

[ Upstream commit eba9ac7abab91c8f6d351460239108bef5e7a0b6 ]

Since commit fa1f68db6ca7 ("drivers: misc: pass miscdevice pointer via
file private data"), the miscdevice stores a pointer to itself inside
filp->private_data, which means that private_data will not be NULL when
wmi_char_open() is called. This might cause memory corruption should
wmi_char_open() be unable to find its driver, something which can
happen when the associated WMI device is deleted in wmi_free_devices().

Fix the problem by using the miscdevice pointer to retrieve the WMI
device data associated with a char device using container_of(). This
also avoids wmi_char_open() picking a wrong WMI device bound to a
driver with the same name as the original driver.

Fixes: 44b6b7661132 ("platform/x86: wmi: create userspace interface for drivers")
Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
Link: https://lore.kernel.org/r/20231020211005.38216-5-W_Armin@xxxxxx
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/platform/x86/wmi.c | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index 0fcfdc574191b..2b79377cc21e2 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -849,21 +849,13 @@ static int wmi_dev_match(struct device *dev, struct device_driver *driver)
 }
 static int wmi_char_open(struct inode *inode, struct file *filp)
 {
-	const char *driver_name = filp->f_path.dentry->d_iname;
-	struct wmi_block *wblock;
-	struct wmi_block *next;
-
-	list_for_each_entry_safe(wblock, next, &wmi_block_list, list) {
-		if (!wblock->dev.dev.driver)
-			continue;
-		if (strcmp(driver_name, wblock->dev.dev.driver->name) == 0) {
-			filp->private_data = wblock;
-			break;
-		}
-	}
+	/*
+	 * The miscdevice already stores a pointer to itself
+	 * inside filp->private_data
+	 */
+	struct wmi_block *wblock = container_of(filp->private_data, struct wmi_block, char_dev);
 
-	if (!filp->private_data)
-		return -ENODEV;
+	filp->private_data = wblock;
 
 	return nonseekable_open(inode, filp);
 }
-- 
2.42.0






[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux