Hi,
On 2/24/22 23:25, Colin King (gmail) wrote:
> Hi,
>
> Static analysis with clang scan has detected a potential issue in the following commit:
>
> commit 2546c60004309ede8e2d1d5341e0decd90e057bf
> Author: David E. Box <david.e.box@xxxxxxxxxxxxxxx>
> Date: Fri Feb 11 17:32:50 2022 -0800
>
> platform/x86: Add Intel Software Defined Silicon driver
>
> The issue is as follows:
>
> static int sdsi_mbox_read(struct sdsi_priv *priv, struct sdsi_mbox_info *info, size_t *data_size)
> {
> int ret;
>
> lockdep_assert_held(&priv->mb_lock);
>
> ret = sdsi_mbox_acquire(priv, info);
> if (ret)
> return ret;
>
> Note: the return above does not assign a value to *data_size
And in this return ret != 0, so we have size==not-set, ret!=0
> return sdsi_mbox_cmd_read(priv, info, data_size);
> }
>
>
> static long state_certificate_read(struct file *filp, struct kobject *kobj,
> struct bin_attribute *attr, char *buf, loff_t off,
> size_t count)
> {
> struct device *dev = kobj_to_dev(kobj);
> struct sdsi_priv *priv = dev_get_drvdata(dev);
> u64 command = SDSI_CMD_READ_STATE;
> struct sdsi_mbox_info info;
> size_t size;
> ^
> Note: size is not initialized
>
> int ret;
>
> if (!priv->sdsi_enabled)
> return -EPERM;
>
> if (off)
> return 0;
>
> /* Buffer for return data */
> info.buffer = kmalloc(SDSI_SIZE_READ_MSG, GFP_KERNEL);
> if (!info.buffer)
> return -ENOMEM;
>
> info.payload = &command;
> info.size = sizeof(command);
>
> ret = mutex_lock_interruptible(&priv->mb_lock);
> if (ret)
> goto free_buffer;
> ret = sdsi_mbox_read(priv, &info, &size);
>
> Note: a failure in scsi_mbox_read can lead to variable size not being assigned a value.
Right if that is true then the following still holds:
size==not-set, ret!=0
>
> mutex_unlock(&priv->mb_lock);
> if (ret < 0)
> goto free_buffer;
>
> Note: failure with ret < 0 going to free_buffer
>
> if (size > count)
> size = count;
>
> memcpy(buf, info.buffer, size);
>
> free_buffer:
> kfree(info.buffer);
>
> if (ret)
> return ret;
This is still valid here: size==not-set, ret!=0
so we hit the true path of the if and return ret, not size.
Regards,
Hans
>
> return size;
>
> Note: uninitialized value in size being returned. This is an error.
>
> }
>
