[PATCH 1/1] media: dib9000: avoid out of bound access

[Heinrich Schuchardt]

The current test to avoid out of bound access to mb[] is insufficient.
For len = 19 non-existent mb[10] will be accessed.

A check in the for loop is insufficient to avoid out of bound access in
dib9000_mbx_send_attr.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@xxxxxx>
---
 drivers/media/dvb-frontends/dib9000.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/media/dvb-frontends/dib9000.c b/drivers/media/dvb-frontends/dib9000.c
index e540cfb..6a71917 100644
--- a/drivers/media/dvb-frontends/dib9000.c
+++ b/drivers/media/dvb-frontends/dib9000.c
@@ -1040,10 +1040,13 @@ static int dib9000_risc_apb_access_write(struct dib9000_state *state, u32 addres
 	if (address >= 1024 || !state->platform.risc.fw_is_running)
 		return -EINVAL;
 
+	if (len > 18)
+		return -EINVAL;
+
 	/* dprintk( "APB access thru wr fw %d %x", address, attribute); */
 
 	mb[0] = (unsigned short)address;
-	for (i = 0; i < len && i < 20; i += 2)
+	for (i = 0; i < len; i += 2)
 		mb[1 + (i / 2)] = (b[i] << 8 | b[i + 1]);
 
 	dib9000_mbx_send_attr(state, OUT_MSG_BRIDGE_APB_W, mb, 1 + len / 2, attribute);
-- 
2.0.0

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