media: mxl5005s: Bounds check size used for max array index

The use of state->CH_Ctrl[i].size in a shift operation implies that its
value can be as much as 32, but the state->CH_Ctrl[i].val array is only
25 in size. Bounds check the size before shifting and looping. Fixes
warnings seen with GCC 13:

../drivers/media/tuners/mxl5005s.c: In function 'MXL_ControlWrite_Group.isra':
../drivers/media/tuners/mxl5005s.c:3450:70: warning: array subscript 32 is above array bounds of 'u16[25]' {aka 'short unsigned int[25]'} [-Warray-bounds=]
 3450 | state->CH_Ctrl[i].val[j] = (u8)((value >> j) & 0x01);
      |  ~~~~~~~~~~~~~~~~~~~~~^~~
../drivers/media/tuners/mxl5005s.c:238:13: note: while referencing 'val'
  238 |         u16 val[25];    /* Binary representation of Value */
      |             ^~~

Cc: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

diff --git a/drivers/media/tuners/mxl5005s.c b/drivers/media/tuners/mxl5005s.c
index 3a50903..06dfab9 100644 (file)
--- a/drivers/media/tuners/mxl5005s.c
+++ b/drivers/media/tuners/mxl5005s.c
@@ -3423,9 +3423,11 @@ static u16 MXL_ControlWrite_Group(struct dvb_frontend *fe, u16 controlNum,
 
                        if (controlNum == state->Init_Ctrl[i].Ctrl_Num) {
 
-                               highLimit = 1 << state->Init_Ctrl[i].size;
+                               u16 size = min_t(u16, state->Init_Ctrl[i].size,
+                                              ARRAY_SIZE(state->Init_Ctrl[i].val));
+                               highLimit = 1 << size;
                                if (value < highLimit) {
-                                       for (j = 0; j < state->Init_Ctrl[i].size; j++) {
+                                       for (j = 0; j < size; j++) {
                                                state->Init_Ctrl[i].val[j] = (u8)((value >> j) & 0x01);
                                                MXL_RegWriteBit(fe, (u8)(state->Init_Ctrl[i].addr[j]),
                                                        (u8)(state->Init_Ctrl[i].bit[j]),
@@ -3442,9 +3444,11 @@ static u16 MXL_ControlWrite_Group(struct dvb_frontend *fe, u16 controlNum,
 
                        if (controlNum == state->CH_Ctrl[i].Ctrl_Num) {
 
-                               highLimit = 1 << state->CH_Ctrl[i].size;
+                               u16 size = min_t(u16, state->CH_Ctrl[i].size,
+                                              ARRAY_SIZE(state->CH_Ctrl[i].val));
+                               highLimit = 1 << size;
                                if (value < highLimit) {
-                                       for (j = 0; j < state->CH_Ctrl[i].size; j++) {
+                                       for (j = 0; j < size; j++) {
                                                state->CH_Ctrl[i].val[j] = (u8)((value >> j) & 0x01);
                                                MXL_RegWriteBit(fe, (u8)(state->CH_Ctrl[i].addr[j]),
                                                        (u8)(state->CH_Ctrl[i].bit[j]),