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Driver core: fix race in dev_driver_string 

This patch (as1310) works around a race in dev_driver_string().  If
the device is unbound while the function is running, dev->driver might
become NULL after we test it and before we dereference it.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
hifive-unleashed-5.1
Alan Stern 2009-12-04 11:06:57 -05:00 committed by Greg Kroah-Hartman
parent c60e0504c8
commit 3589972e51
1 changed files with 8 additions and 1 deletions
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9
drivers/base/core.c
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@ -56,7 +56,14 @@ static inline int device_is_not_partition(struct device *dev)
*/
const char *dev_driver_string(const struct device *dev)
{
return dev->driver ? dev->driver->name :
struct device_driver *drv;
/* dev->driver can change to NULL underneath us because of unbinding,
* so be careful about accessing it. dev->bus and dev->class should
* never change once they are set, so they don't need special care.
*/
drv = ACCESS_ONCE(dev->driver);
return drv ? drv->name :
(dev->bus ? dev->bus->name :
(dev->class ? dev->class->name : ""));
}