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    Subject[PATCH 3.16 201/305] Btrfs: ensure path name is null terminated at btrfs_control_ioctl
    3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Filipe Manana <fdmanana@suse.com>

    commit f505754fd6599230371cb01b9332754ddc104be1 upstream.

    We were using the path name received from user space without checking that
    it is null terminated. While btrfs-progs is well behaved and does proper
    validation and null termination, someone could call the ioctl and pass
    a non-null terminated patch, leading to buffer overrun problems in the
    kernel. The ioctl is protected by CAP_SYS_ADMIN.

    So just set the last byte of the path to a null character, similar to what
    we do in other ioctls (add/remove/resize device, snapshot creation, etc).

    Reviewed-by: Anand Jain <anand.jain@oracle.com>
    Signed-off-by: Filipe Manana <fdmanana@suse.com>
    Reviewed-by: David Sterba <dsterba@suse.com>
    Signed-off-by: David Sterba <dsterba@suse.com>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    fs/btrfs/super.c | 1 +
    1 file changed, 1 insertion(+)

    --- a/fs/btrfs/super.c
    +++ b/fs/btrfs/super.c
    @@ -1771,6 +1771,7 @@ static long btrfs_control_ioctl(struct f
    vol = memdup_user((void __user *)arg, sizeof(*vol));
    if (IS_ERR(vol))
    return PTR_ERR(vol);
    + vol->name[BTRFS_PATH_NAME_MAX] = '\0';

    switch (cmd) {
    case BTRFS_IOC_SCAN_DEV:
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