Messages in this thread | | | Date | Tue, 17 May 2022 10:50:08 -0500 | Subject | Re: [PATCH v3] crypto: ccp - Use kzalloc for sev ioctl interfaces to prevent kernel memory leak | From | Tom Lendacky <> |
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On 5/17/22 10:39, 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 and memset the data buffer to zero in > sev_ioctl_do_platform_status. > > Fixes: e799035609e15 ("crypto: ccp: Implement SEV_PEK_CSR ioctl command") > Fixes: 76a2b524a4b1d ("crypto: ccp: Implement SEV_PDH_CERT_EXPORT ioctl command") > Fixes: d6112ea0cb344 ("crypto: ccp - introduce SEV_GET_ID2 command") > Cc: stable@vger.kernel.org > Reported-by: Andy Nguyen <theflow@google.com> > Suggested-by: David Rientjes <rientjes@google.com> > Suggested-by: Peter Gonda <pgonda@google.com> > Signed-off-by: John Allen <john.allen@amd.com> > --- > v2: > - Add fixes tags and CC stable@vger.kernel.org > v3: > - memset data buffer to zero in sev_ioctl_do_platform_status > --- > drivers/crypto/ccp/sev-dev.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c > index 6ab93dfd478a..da143cc3a8f5 100644 > --- a/drivers/crypto/ccp/sev-dev.c > +++ b/drivers/crypto/ccp/sev-dev.c > @@ -551,6 +551,8 @@ static int sev_ioctl_do_platform_status(struct sev_issue_cmd *argp) > struct sev_user_data_status data; > int ret; > > + memset(&data, 0, sizeof(data)); > +
Probably needs an additional Fixes: tag now?
Fixes: 38103671aad3 ("crypto: ccp: Use the stack and common buffer for status commands")
Thanks, Tom
> ret = __sev_do_cmd_locked(SEV_CMD_PLATFORM_STATUS, &data, &argp->error); > if (ret) > return ret; > @@ -604,7 +606,7 @@ 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 +830,7 @@ 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 +949,14 @@ 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;
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