I apologize for the long delay, this reply got lost in my inbox. I've
added an updated patch below:
i2c_smbus_xfer() does not always fill an entire block, allowing
kernel stack memory disclosure through the temp variable. Clear
it before it's read to.
Signed-off-by: Vlad Tsyrklevich <vlad@xxxxxxxxxxxxxxx>
---
drivers/i2c/i2c-dev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 66f323f..6f638bb 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -331,7 +331,7 @@ static noinline int i2cdev_ioctl_smbus(struct
i2c_client *client,
unsigned long arg)
{
struct i2c_smbus_ioctl_data data_arg;
- union i2c_smbus_data temp;
+ union i2c_smbus_data temp = {};
int datasize, res;
if (copy_from_user(&data_arg,
On Tue, Oct 25, 2016 at 4:45 PM, Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote:
> On Tue, Oct 11, 2016 at 02:52:28PM +0200, Vlad Tsyrklevich wrote:
>> i2c_smbus_xfer() does not always fill an entire block, allowing
>> kernel stack memory disclosure through the temp variable. Clear
>> it before it's read to.
>>
>> Signed-off-by: Vlad Tsyrklevich <vlad@xxxxxxxxxxxxxxx>
>
> Yes, thanks. But what about clearing 'temp' when it is declared? This
> would be rock-solid for all future code paths.
>
>>
>> ---
>> drivers/i2c/i2c-dev.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
>> index 66f323f..62cb111 100644
>> --- a/drivers/i2c/i2c-dev.c
>> +++ b/drivers/i2c/i2c-dev.c
>> @@ -393,6 +393,8 @@ static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
>> (data_arg.read_write == I2C_SMBUS_WRITE)) {
>> if (copy_from_user(&temp, data_arg.data, datasize))
>> return -EFAULT;
>> + } else {
>> + memset(&temp, 0, datasize);
>> }
>> if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
>> /* Convert old I2C block commands to the new
>> --
>> 2.7.0
>>
--
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