si4713-i2c: avoid potential buffer overflow on si4713, CVE-2011-2700

BugLink: http://bugs.launchpad.net/bugs/844370
CVE-2011-2700

While compiling it with Fedora 15, I noticed this issue:

  inlined from ‘si4713_write_econtrol_string’ at drivers/media/radio/si4713-i2c.c:1065:24:
  arch/x86/include/asm/uaccess_32.h:211:26: error: call to ‘copy_from_user_overflow’ declared with attribute error: copy_from_user() buffer size is not provably correct

Cc: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
Acked-by: Eduardo Valentin <edubezval@gmail.com>
Reviewed-by: Eugene Teo <eugeneteo@kernel.sg>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit dc6b845044ccb7e9e6f3b7e71bd179b3cf0223b6)

Signed-off-by: Andy Whitcroft <andy.whitcroft@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/drivers/media/radio/si4713-i2c.c b/drivers/media/radio/si4713-i2c.c
index 0fab6f8..924445a 100644 (file)
--- a/drivers/media/radio/si4713-i2c.c
+++ b/drivers/media/radio/si4713-i2c.c
@@ -1033,7 +1033,7 @@ static int si4713_write_econtrol_string(struct si4713_device *sdev,
                char ps_name[MAX_RDS_PS_NAME + 1];
 
                len = control->size - 1;
-               if (len > MAX_RDS_PS_NAME) {
+               if (len < 0 || len > MAX_RDS_PS_NAME) {
                        rval = -ERANGE;
                        goto exit;
                }
@@ -1057,7 +1057,7 @@ static int si4713_write_econtrol_string(struct si4713_device *sdev,
                char radio_text[MAX_RDS_RADIO_TEXT + 1];
 
                len = control->size - 1;
-               if (len > MAX_RDS_RADIO_TEXT) {
+               if (len < 0 || len > MAX_RDS_RADIO_TEXT) {
                        rval = -ERANGE;
                        goto exit;
                }