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Commit 5b06470816fb5e658e81db2a55b530ff2ba711c9

Authored by Oliver Neukum
Committed by Greg Kroah-Hartman
1 parent 57e4f041bf
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

USB: fix autosuspend race in skeleton driver 

as the skeleton driver was made ready for autosuspend a race condition
was introduced. The reference to get device must be gotten before the
autosuspend counter is upped, as this operation may sleep, dropping BKL.
Dropping BKL means that the pointer to the device may become invalid.
Here's the fix.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Showing 1 changed file with 6 additions and 4 deletions Side-by-side Diff

drivers/usb/usb-skeleton.c
Diff comments   View file @ 5b06470
... ... @@ -90,13 +90,15 @@
90 90 goto exit;
91 91 }
92 92  
  93 + /* increment our usage count for the device */
  94 + kref_get(&dev->kref);
  95 +
93 96 /* prevent the device from being autosuspended */
94 97 retval = usb_autopm_get_interface(interface);
95   - if (retval)
  98 + if (retval) {
  99 + kref_put(&dev->kref, skel_delete);
96 100 goto exit;
97   -
98   - /* increment our usage count for the device */
99   - kref_get(&dev->kref);
  101 + }
100 102  
101 103 /* save our object in the file's private structure */
102 104 file->private_data = dev;