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btrfs: read entire device info under lock
There's a theoretical possibility of reading stale (or even more theoretically, freed) data from DEV_INFO ioctl when the device would disappear between an early mutex unlock and data being copied from the device structure. Signed-off-by: David Sterba <dsterba@suse.cz> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
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@ -2432,7 +2432,6 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
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mutex_lock(&fs_devices->device_list_mutex);
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dev = btrfs_find_device(root->fs_info, di_args->devid, s_uuid, NULL);
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mutex_unlock(&fs_devices->device_list_mutex);
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if (!dev) {
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ret = -ENODEV;
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@ -2456,6 +2455,7 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
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}
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out:
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mutex_unlock(&fs_devices->device_list_mutex);
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if (ret == 0 && copy_to_user(arg, di_args, sizeof(*di_args)))
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ret = -EFAULT;
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