[bug report] cxd2820r: dynamically allocated arrays

[bug report] cxd2820r: dynamically allocated arrays

[Dan Carpenter]

This driver has several places that use dynamically sized arrays.
It's dangerous to do that in the kernel because the kernel has a
very small stack.  A bug could cause the stack to overflow and
corrupt memory.  I seem to recall i2c transfers can be triggered by
the users but I don't know the details (ie security implications).

Here is an example of what I mean:

static int cxd2820r_tuner_i2c_xfer(struct i2c_adapter *i2c_adap,
        struct i2c_msg msg[], int num)
{
        struct cxd2820r_priv *priv = i2c_get_adapdata(i2c_adap);
        u8 obuf[msg[0].len + 2];
                ^^^^^^^^^^
        struct i2c_msg msg2[2] = {

If msg[0].len is too long it will overflow.

Here is the sparse output for the file:

  CHECK   drivers/media/dvb/frontends/cxd2820r_core.c
drivers/media/dvb/frontends/cxd2820r.h:58:30: error: dubious one-bit signed bitfield
drivers/media/dvb/frontends/cxd2820r.h:64:23: error: dubious one-bit signed bitfield
drivers/media/dvb/frontends/cxd2820r_priv.h:58:26: error: dubious one-bit signed bitfield
drivers/media/dvb/frontends/cxd2820r_priv.h:64:31: error: dubious one-bit signed bitfield
drivers/media/dvb/frontends/cxd2820r_core.c:33:19: error: bad constant expression
drivers/media/dvb/frontends/cxd2820r_core.c:38:32: error: cannot size expression
drivers/media/dvb/frontends/cxd2820r_core.c:61:16: error: bad constant expression
drivers/media/dvb/frontends/cxd2820r_core.c:71:32: error: cannot size expression
drivers/media/dvb/frontends/cxd2820r_core.c:743:28: error: bad constant expression
drivers/media/dvb/frontends/cxd2820r_core.c:748:32: error: cannot size expression
drivers/media/dvb/frontends/cxd2820r_core.c:762:31: error: cannot size expression
  CC [M]  drivers/media/dvb/frontends/cxd2820r_core.o

regards,
dan carpenter

Re: [bug report] cxd2820r: dynamically allocated arrays

[Antti Palosaari]

Hello Dan,

I am just fixing those and also some other fixes.

regards,
Antti

On 05/25/2011 05:42 PM, Dan Carpenter wrote:
> This driver has several places that use dynamically sized arrays.
> It's dangerous to do that in the kernel because the kernel has a
> very small stack.  A bug could cause the stack to overflow and
> corrupt memory.  I seem to recall i2c transfers can be triggered by
> the users but I don't know the details (ie security implications).
>
> Here is an example of what I mean:
>
> static int cxd2820r_tuner_i2c_xfer(struct i2c_adapter *i2c_adap,
>          struct i2c_msg msg[], int num)
> {
>          struct cxd2820r_priv *priv = i2c_get_adapdata(i2c_adap);
>          u8 obuf[msg[0].len + 2];
>                  ^^^^^^^^^^
>          struct i2c_msg msg2[2] = {
>
> If msg[0].len is too long it will overflow.
>
> Here is the sparse output for the file:
>
>    CHECK   drivers/media/dvb/frontends/cxd2820r_core.c
> drivers/media/dvb/frontends/cxd2820r.h:58:30: error: dubious one-bit signed bitfield
> drivers/media/dvb/frontends/cxd2820r.h:64:23: error: dubious one-bit signed bitfield
> drivers/media/dvb/frontends/cxd2820r_priv.h:58:26: error: dubious one-bit signed bitfield
> drivers/media/dvb/frontends/cxd2820r_priv.h:64:31: error: dubious one-bit signed bitfield
> drivers/media/dvb/frontends/cxd2820r_core.c:33:19: error: bad constant expression
> drivers/media/dvb/frontends/cxd2820r_core.c:38:32: error: cannot size expression
> drivers/media/dvb/frontends/cxd2820r_core.c:61:16: error: bad constant expression
> drivers/media/dvb/frontends/cxd2820r_core.c:71:32: error: cannot size expression
> drivers/media/dvb/frontends/cxd2820r_core.c:743:28: error: bad constant expression
> drivers/media/dvb/frontends/cxd2820r_core.c:748:32: error: cannot size expression
> drivers/media/dvb/frontends/cxd2820r_core.c:762:31: error: cannot size expression
>    CC [M]  drivers/media/dvb/frontends/cxd2820r_core.o
>
> regards,
> dan carpenter


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