[PATCH #upstream-fixes] libata: don't allow sysfs read access to force param

[Tejun Heo <htejun@gmail.com>]

Buffer for force param is deallocated after initialization, so trying
to read it via sysfs results in oops.  Don't allow read access to the
param node.

Spotted by Eric Sesterhenn.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Eric Sesterhenn <snakebyte@gmx.de>
---
 drivers/ata/libata-core.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 4fbcce7..e399eaa 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -106,7 +106,8 @@ static struct ata_force_ent *ata_force_tbl;
 static int ata_force_tbl_size;
 
 static char ata_force_param_buf[PAGE_SIZE] __initdata;
-module_param_string(force, ata_force_param_buf, sizeof(ata_force_param_buf), 0444);
+/* param_buf is thrown away after initialization, disallow read */
+module_param_string(force, ata_force_param_buf, sizeof(ata_force_param_buf), 0);
 MODULE_PARM_DESC(force, "Force ATA configurations including cable type, link speed and transfer mode (see Documentation/kernel-parameters.txt for details)");
 
 int atapi_enabled = 1;