On Wed, Jun 18, 2014 at 3:02 PM, Heinrich Schuchardt <xypron.glpk@xxxxxx> wrote: > 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]); Good catch on the mb[] access! However, I think there is still more to fix since b[i + 1] can read past the end of b: Say b is defined as "u8 b[3]". Passing len 3 means the second loop, with i==2 will access b[2] and b[3], the latter is out of range. -Kees > > dib9000_mbx_send_attr(state, OUT_MSG_BRIDGE_APB_W, mb, 1 + len / 2, attribute); > -- > 2.0.0 > -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
