Description of problem:
The megaraid_sas driver exposes a number of driver attributes in sysfs. Many of these are read-only, just export information from the driver and are world-readable.

A couple of attributes are writable and may be used to change the behaviour of the driver (e.g. setting debug logging levels, selecting poll vs. interrupt I/O mode etc).

Some of these writable attributes are mistakenly created with world-writable permissions, e.g. dbg_lvl and poll_mode_io:

rw-rw-rw- root root  /sys/bus/pci/drivers/megaraid_sas/dbg_lvl
rw-rw-rw- root root  /sys/bus/pci/drivers/megaraid_sas/poll_mode_io

$ grep 'DRIVER_ATTR.*S_IWUGO' drivers/scsi/megaraid/megaraid_sas.c 
static DRIVER_ATTR(dbg_lvl, S_IRUGO|S_IWUGO, megasas_sysfs_show_dbg_lvl,
static DRIVER_ATTR(poll_mode_io, S_IRUGO|S_IWUGO,

This would allow an unprivileged user to affect kernel driver behaviour and logging level.

Version-Release number of selected component (if applicable):
2.6.18-*.el5

How reproducible:
100%

Steps to Reproduce:
(On a system with megaraid_sas loaded)
1. ls -l /sys/bus/pci/drivers/megaraid_sas/dbg_lvl
2. ls -l /sys/bus/pci/drivers/megaraid_sas/poll_mode_io

  
Actual results:
rw-rw-rw- root root  /sys/bus/pci/drivers/megaraid_sas/dbg_lvl
rw-rw-rw- root root  /sys/bus/pci/drivers/megaraid_sas/poll_mode_io

Expected results:
rw------- root root  /sys/bus/pci/drivers/megaraid_sas/dbg_lvl
rw------- root root  /sys/bus/pci/drivers/megaraid_sas/poll_mode_io

Additional info:

Upstream made the dbd_lvl permissions more restrictive:

commit 66dca9b8c50b5e59d3bea8b21cee5c6dae6c9c46
Author: Joe Malicki <jmalicki>
Date:   Thu Aug 14 17:14:48 2008 -0400

    [SCSI] megaraid_sas: remove sysfs dbg_lvl world writeable permissions
    
    /sys/bus/pci/drivers/megaraid_sas/dbg_lvl defaults to being
    world-writable, which seems bad (letting any user affect kernel driver
    behavior and logging level).
    
    This turns off group and user write permissions, so that on typical
    production systems only root can write to it.
    
    [jejb: fix up rejections]
    Signed-off-by: Joseph Malicki <jmalicki>
    Acked-by: "Yang, Bo" <Bo.Yang>
    Signed-off-by: James Bottomley <James.Bottomley>

The poll_mode_io pseudofile still has world-writable permissions upstream.