• Douglas Gilbert's avatar
    sg: fix dxferp in from_to case · 5ecee0a3
    Douglas Gilbert authored
    One of the strange things that the original sg driver did was let the
    user provide both a data-out buffer (it followed the sg_header+cdb)
    _and_ specify a reply length greater than zero. What happened was that
    the user data-out buffer was copied into some kernel buffers and then
    the mid level was told a read type operation would take place with the
    data from the device overwriting the same kernel buffers. The user would
    then read those kernel buffers back into the user space.
    
    From what I can tell, the above action was broken by commit fad7f01e
    ("sg: set dxferp to NULL for READ with the older SG interface") in 2008
    and syzkaller found that out recently.
    
    Make sure that a user space pointer is passed through when data follows
    the sg_header structure and command.  Fix the abnormal case when a
    non-zero reply_len is also given.
    
    Fixes: fad7f01e
    Cc: <stable@vger.kernel.org> #v2.6.28+
    Signed-off-by: default avatarDouglas Gilbert <dgilbert@interlog.com>
    Reviewed-by: default avatarEwan Milne <emilne@redhat.com>
    Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
    5ecee0a3