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usb: gadget: f_fs: Stop ffs_closed NULL pointer dereference 

The struct ffs_data::private_data has a pointer to
ffs_dev stored in it during the ffs_fs_mount() function
however it is not cleared when the ffs_dev is freed
later which causes the ffs_closed function to crash
with "Unable to handle kernel NULL pointer dereference"
error when using the data in ffs_data::private_data.

This clears this pointer during the ffs_free_dev clean
up function.

Signed-off-by: Jim Baxter <jim_baxter@mentor.com>
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Harish Jenny K N <harish_kandiga@mentor.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This commit is contained in:
Jim Baxter 2016-09-08 11:18:16 +02:00 committed by Felipe Balbi
parent 9d6173e125
commit 3262ad8243
1 changed files with 5 additions and 0 deletions
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5
drivers/usb/gadget/function/f_fs.c
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@ -3502,6 +3502,11 @@ static void _ffs_free_dev(struct ffs_dev *dev)
list_del(&dev->entry);
if (dev->name_allocated)
kfree(dev->name);
/* Clear the private_data pointer to stop incorrect dev access */
if (dev->ffs_data)
dev->ffs_data->private_data = NULL;
kfree(dev);
if (list_empty(&ffs_devices))
functionfs_cleanup();