[PATCH] i2c: xgene-slimpro: Fix out-of-bounds bug in xgene_slimpro_i2c_xfer()

[PATCH] i2c: xgene-slimpro: Fix out-of-bounds bug in xgene_slimpro_i2c_xfer()

[Wei Chen]

The data->block[0] variable comes from user and is a number between
0-255. Without proper check, the variable may be very large to cause
an out-of-bounds when performing memcpy in slimpro_i2c_blkwr.

Fix this bug by checking the value of data->block[0].

Signed-off-by: Wei Chen <harperchen1110@gmail.com>
---
 drivers/i2c/busses/i2c-xgene-slimpro.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/i2c/busses/i2c-xgene-slimpro.c b/drivers/i2c/busses/i2c-xgene-slimpro.c
index 63259b3ea5ab..bc9a3e7e0c96 100644
--- a/drivers/i2c/busses/i2c-xgene-slimpro.c
+++ b/drivers/i2c/busses/i2c-xgene-slimpro.c
@@ -391,6 +391,10 @@ static int xgene_slimpro_i2c_xfer(struct i2c_adapter *adap, u16 addr,
 						&data->block[0]);
 
 		} else {
+
+			if (data->block[0] + 1 > I2C_SMBUS_BLOCK_MAX)
+				return -EINVAL;
+
 			ret = slimpro_i2c_blkwr(ctx, addr, command,
 						SMBUS_CMD_LEN,
 						SLIMPRO_IIC_SMB_PROTOCOL,
@@ -408,6 +412,10 @@ static int xgene_slimpro_i2c_xfer(struct i2c_adapter *adap, u16 addr,
 						IIC_SMB_WITHOUT_DATA_LEN,
 						&data->block[1]);
 		} else {
+
+			if (data->block[0] > I2C_SMBUS_BLOCK_MAX)
+				return -EINVAL;
+
 			ret = slimpro_i2c_blkwr(ctx, addr, command,
 						SMBUS_CMD_LEN,
 						SLIMPRO_IIC_I2C_PROTOCOL,
-- 
2.25.1

Re: [PATCH] i2c: xgene-slimpro: Fix out-of-bounds bug in xgene_slimpro_i2c_xfer()

[Andi Shyti]

Hi Wei,

On Tue, Mar 14, 2023 at 01:57:34PM +0000, Wei Chen wrote:
> The data->block[0] variable comes from user and is a number between
> 0-255. Without proper check, the variable may be very large to cause
> an out-of-bounds when performing memcpy in slimpro_i2c_blkwr.
> 
> Fix this bug by checking the value of data->block[0].
> 
> Signed-off-by: Wei Chen <harperchen1110@gmail.com>
> ---
>  drivers/i2c/busses/i2c-xgene-slimpro.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-xgene-slimpro.c b/drivers/i2c/busses/i2c-xgene-slimpro.c
> index 63259b3ea5ab..bc9a3e7e0c96 100644
> --- a/drivers/i2c/busses/i2c-xgene-slimpro.c
> +++ b/drivers/i2c/busses/i2c-xgene-slimpro.c
> @@ -391,6 +391,10 @@ static int xgene_slimpro_i2c_xfer(struct i2c_adapter *adap, u16 addr,
>  						&data->block[0]);
>  
>  		} else {
> +
> +			if (data->block[0] + 1 > I2C_SMBUS_BLOCK_MAX)
> +				return -EINVAL;
> +
>  			ret = slimpro_i2c_blkwr(ctx, addr, command,
>  						SMBUS_CMD_LEN,
>  						SLIMPRO_IIC_SMB_PROTOCOL,
> @@ -408,6 +412,10 @@ static int xgene_slimpro_i2c_xfer(struct i2c_adapter *adap, u16 addr,
>  						IIC_SMB_WITHOUT_DATA_LEN,
>  						&data->block[1]);
>  		} else {
> +
> +			if (data->block[0] > I2C_SMBUS_BLOCK_MAX)
> +				return -EINVAL;
> +

you could eventually put this check inside slimpro_i2c_blkwr() so
that you have it once and for all, for everyone.

Andi

>  			ret = slimpro_i2c_blkwr(ctx, addr, command,
>  						SMBUS_CMD_LEN,
>  						SLIMPRO_IIC_I2C_PROTOCOL,
> -- 
> 2.25.1
> 

Re: [PATCH v2] i2c: xgene-slimpro: Fix out-of-bounds bug in xgene_slimpro_i2c_xfer()

[Wei Chen]

The data->block[0] variable comes from user and is a number between
0-255. Without a proper check, the variable may be very large to cause
an out-of-bounds when performing memcpy in slimpro_i2c_blkwr.

Fix this bug by checking the value of writelen.

Signed-off-by: Wei Chen <harperchen1110@gmail.com>
---
Changes in v2:
 - Put length check inside slimpro_i2c_blkwr

drivers/i2c/busses/i2c-xgene-slimpro.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/i2c/busses/i2c-xgene-slimpro.c
b/drivers/i2c/busses/i2c-xgene-slimpro.c
index bc9a3e7e0c96..0f7263e2276a 100644
--- a/drivers/i2c/busses/i2c-xgene-slimpro.c
+++ b/drivers/i2c/busses/i2c-xgene-slimpro.c
@@ -308,6 +308,9 @@ static int slimpro_i2c_blkwr(struct
slimpro_i2c_dev *ctx, u32 chip,
u32 msg[3];
int rc;
+ if (writelen > I2C_SMBUS_BLOCK_MAX)
+ return -EINVAL;
+
memcpy(ctx->dma_buffer, data, writelen);
paddr = dma_map_single(ctx->dev, ctx->dma_buffer, writelen,
DMA_TO_DEVICE);
-- 
2.25.1


On Tue, 14 Mar 2023 at 22:10, Andi Shyti <andi.shyti@kernel.org> wrote:
>
> Hi Wei,
>
> On Tue, Mar 14, 2023 at 01:57:34PM +0000, Wei Chen wrote:
> > The data->block[0] variable comes from user and is a number between
> > 0-255. Without proper check, the variable may be very large to cause
> > an out-of-bounds when performing memcpy in slimpro_i2c_blkwr.
> >
> > Fix this bug by checking the value of data->block[0].
> >
> > Signed-off-by: Wei Chen <harperchen1110@gmail.com>
> > ---
> >  drivers/i2c/busses/i2c-xgene-slimpro.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-xgene-slimpro.c b/drivers/i2c/busses/i2c-xgene-slimpro.c
> > index 63259b3ea5ab..bc9a3e7e0c96 100644
> > --- a/drivers/i2c/busses/i2c-xgene-slimpro.c
> > +++ b/drivers/i2c/busses/i2c-xgene-slimpro.c
> > @@ -391,6 +391,10 @@ static int xgene_slimpro_i2c_xfer(struct i2c_adapter *adap, u16 addr,
> >                                               &data->block[0]);
> >
> >               } else {
> > +
> > +                     if (data->block[0] + 1 > I2C_SMBUS_BLOCK_MAX)
> > +                             return -EINVAL;
> > +
> >                       ret = slimpro_i2c_blkwr(ctx, addr, command,
> >                                               SMBUS_CMD_LEN,
> >                                               SLIMPRO_IIC_SMB_PROTOCOL,
> > @@ -408,6 +412,10 @@ static int xgene_slimpro_i2c_xfer(struct i2c_adapter *adap, u16 addr,
> >                                               IIC_SMB_WITHOUT_DATA_LEN,
> >                                               &data->block[1]);
> >               } else {
> > +
> > +                     if (data->block[0] > I2C_SMBUS_BLOCK_MAX)
> > +                             return -EINVAL;
> > +
>
> you could eventually put this check inside slimpro_i2c_blkwr() so
> that you have it once and for all, for everyone.
>
> Andi
>
> >                       ret = slimpro_i2c_blkwr(ctx, addr, command,
> >                                               SMBUS_CMD_LEN,
> >                                               SLIMPRO_IIC_I2C_PROTOCOL,
> > --
> > 2.25.1
> >

Re: [PATCH v2] i2c: xgene-slimpro: Fix out-of-bounds bug in xgene_slimpro_i2c_xfer()

[Andi Shyti]

Hi Wei,

On Tue, Mar 14, 2023 at 11:43:41PM +0800, Wei Chen wrote:
> The data->block[0] variable comes from user and is a number between
> 0-255. Without a proper check, the variable may be very large to cause
> an out-of-bounds when performing memcpy in slimpro_i2c_blkwr.
> 
> Fix this bug by checking the value of writelen.
> 
> Signed-off-by: Wei Chen <harperchen1110@gmail.com>

I forgot to check earlier, can you also add:

Fixes: f6505fbabc42 ("i2c: add SLIMpro I2C device driver on APM X-Gene platform")
Cc: stable@vger.kernel.org

> ---
> Changes in v2:
>  - Put length check inside slimpro_i2c_blkwr
> 
> drivers/i2c/busses/i2c-xgene-slimpro.c | 3 +++
> 1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-xgene-slimpro.c
> b/drivers/i2c/busses/i2c-xgene-slimpro.c
> index bc9a3e7e0c96..0f7263e2276a 100644
> --- a/drivers/i2c/busses/i2c-xgene-slimpro.c
> +++ b/drivers/i2c/busses/i2c-xgene-slimpro.c
> @@ -308,6 +308,9 @@ static int slimpro_i2c_blkwr(struct
> slimpro_i2c_dev *ctx, u32 chip,
> u32 msg[3];
> int rc;
> + if (writelen > I2C_SMBUS_BLOCK_MAX)
> + return -EINVAL;
> +

There is something odd looking here. Can you please fix the
formatting and leave one blank line from the variable declaration
and the 'if (...'.

Remember, please, to run checkpatch.pl before sending the patch.

Andi