[media] r820t: avoid potential memcpy buffer overflow in shadow_store()

The memcpy in shadow_store() could exceed buffer limits when r > 0.

Signed-off-by: Gianluca Gennari <gennarone@gmail.com>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/media/tuners/r820t.c b/drivers/media/tuners/r820t.c
index 63062a9b4003..0a5f96be08f1 100644
--- a/drivers/media/tuners/r820t.c
+++ b/drivers/media/tuners/r820t.c
@@ -364,8 +364,8 @@ static void shadow_store(struct r820t_priv *priv, u8 reg, const u8 *val,
         }
         if (len <= 0)
                 return;
-        if (len > NUM_REGS)
-                len = NUM_REGS;
+        if (len > NUM_REGS - r)
+                len = NUM_REGS - r;
 
         tuner_dbg("%s: prev  reg=%02x len=%d: %*ph\n",
                   __func__, r + REG_SHADOW_START, len, len, val);