On Thu, May 12, 2022 at 08:34:55PM +0000, John Allen wrote:
> For some sev ioctl interfaces, input may be passed that is less than or
> equal to SEV_FW_BLOB_MAX_SIZE, but larger than the data that PSP
> firmware returns. In this case, kmalloc will allocate memory that is the
> size of the input rather than the size of the data. Since PSP firmware
> doesn't fully overwrite the buffer, the sev ioctl interfaces with the
> issue may return uninitialized slab memory.
>
> Currently, all of the ioctl interfaces in the ccp driver are safe, but
> to prevent future problems, change all ioctl interfaces that allocate
> memory with kmalloc to use kzalloc.
I should have CC'd stable@xxxxxxxxxxxxxxx and added a Fixes tag for
this. I'll send a v2 with these, but I'll give it a couple days for
comments before I do.
Thanks,
John
>
> Reported-by: Andy Nguyen <theflow@xxxxxxxxxx>
> Suggested-by: David Rientjes <rientjes@xxxxxxxxxx>
> Suggested-by: Peter Gonda <pgonda@xxxxxxxxxx>
> Signed-off-by: John Allen <john.allen@xxxxxxx>
> ---
> drivers/crypto/ccp/sev-dev.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 6ab93dfd478a..e2298843ea8a 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -604,7 +604,7 @@ static int sev_ioctl_do_pek_csr(struct sev_issue_cmd *argp, bool writable)
> if (input.length > SEV_FW_BLOB_MAX_SIZE)
> return -EFAULT;
>
> - blob = kmalloc(input.length, GFP_KERNEL);
> + blob = kzalloc(input.length, GFP_KERNEL);
> if (!blob)
> return -ENOMEM;
>
> @@ -828,7 +828,7 @@ static int sev_ioctl_do_get_id2(struct sev_issue_cmd *argp)
> input_address = (void __user *)input.address;
>
> if (input.address && input.length) {
> - id_blob = kmalloc(input.length, GFP_KERNEL);
> + id_blob = kzalloc(input.length, GFP_KERNEL);
> if (!id_blob)
> return -ENOMEM;
>
> @@ -947,14 +947,14 @@ static int sev_ioctl_do_pdh_export(struct sev_issue_cmd *argp, bool writable)
> if (input.cert_chain_len > SEV_FW_BLOB_MAX_SIZE)
> return -EFAULT;
>
> - pdh_blob = kmalloc(input.pdh_cert_len, GFP_KERNEL);
> + pdh_blob = kzalloc(input.pdh_cert_len, GFP_KERNEL);
> if (!pdh_blob)
> return -ENOMEM;
>
> data.pdh_cert_address = __psp_pa(pdh_blob);
> data.pdh_cert_len = input.pdh_cert_len;
>
> - cert_blob = kmalloc(input.cert_chain_len, GFP_KERNEL);
> + cert_blob = kzalloc(input.cert_chain_len, GFP_KERNEL);
> if (!cert_blob) {
> ret = -ENOMEM;
> goto e_free_pdh;
> --
> 2.34.1
>
