| Date | Wed, 16 Dec 2009 19:55:59 -0800 | From | Greg KH <> | Subject | [062/151] Driver core: fix race in dev_driver_string |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: Alan Stern <stern@rowland.harvard.edu>
commit 3589972e51fac1e02d0aaa576fa47f568cb94d40 upstream.
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: Oliver Neukum <oliver@neukum.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/base/core.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -56,7 +56,14 @@ static inline int device_is_not_partitio */ 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 : "")); }
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