[media] rc: ir-lirc-codec: fix potential integer overflow

'n' may be bigger than MAX_INT*sizeof(int), if so checking of truncated
(int)(n/sizeof(int)) for LIRCBUF_SIZE overflow and then using nontruncated 'count'
doesn't make sense.  Also n may be up to sizeof(int)-1 bytes bigger than expected,
so check value of (n % sizeof(int)) too.

Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/media/rc/ir-lirc-codec.c b/drivers/media/rc/ir-lirc-codec.c
index 1e87ee8e5c99..f011c5d9dea1 100644
--- a/drivers/media/rc/ir-lirc-codec.c
+++ b/drivers/media/rc/ir-lirc-codec.c
@@ -100,7 +100,8 @@ static ssize_t ir_lirc_transmit_ir(struct file *file, const char *buf,
         struct lirc_codec *lirc;
         struct rc_dev *dev;
         int *txbuf; /* buffer with values to transmit */
-        int ret = 0, count;
+        int ret = 0;
+        size_t count;
 
         lirc = lirc_get_pdata(file);
         if (!lirc)
@@ -110,7 +111,7 @@ static ssize_t ir_lirc_transmit_ir(struct file *file, const char *buf,
                 return -EINVAL;
 
         count = n / sizeof(int);
-        if (count > LIRCBUF_SIZE || count % 2 == 0)
+        if (count > LIRCBUF_SIZE || count % 2 == 0 || n % sizeof(int) != 0)
                 return -EINVAL;
 
         txbuf = memdup_user(buf, n);