drivers: media: dvb-frontends/rtl2830: fix an out-of-bounds write error

Ensure index in rtl2830_pid_filter does not exceed 31 to prevent
out-of-bounds access.

dev->filters is a 32-bit value, so set_bit and clear_bit functions should
only operate on indices from 0 to 31. If index is 32, it will attempt to
access a non-existent 33rd bit, leading to out-of-bounds access.
Change the boundary check from index > 32 to index >= 32 to resolve this
issue.

Fixes: df70ddad81b4 ("[media] rtl2830: implement PID filter")
Signed-off-by: Junlin Li <make24@iscas.ac.cn>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

diff --git a/drivers/media/dvb-frontends/rtl2830.c b/drivers/media/dvb-frontends/rtl2830.c
index a1e62d4..aa4ef9a 100644 (file)
--- a/drivers/media/dvb-frontends/rtl2830.c
+++ b/drivers/media/dvb-frontends/rtl2830.c
@@ -609,7 +609,7 @@ static int rtl2830_pid_filter(struct dvb_frontend *fe, u8 index, u16 pid, int on
                index, pid, onoff);
 
        /* skip invalid PIDs (0x2000) */
-       if (pid > 0x1fff || index > 32)
+       if (pid > 0x1fff || index >= 32)
                return 0;
 
        if (onoff)