From: Ashish Kalra ashish.kalra@amd.com

For some sev ioctl interfaces, the length parameter that is passed maybe 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 allocated buffer, these sev ioctl interface may return uninitialized kernel slab memory.

Reported-by: Andy Nguyen theflow@google.com Suggested-by: David Rientjes rientjes@google.com Suggested-by: Peter Gonda pgonda@google.com Cc: kvm@vger.kernel.org Cc: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org Fixes: eaf78265a4ab3 ("KVM: SVM: Move SEV code to separate file") Fixes: 2c07ded06427d ("KVM: SVM: add support for SEV attestation command") Fixes: 4cfdd47d6d95a ("KVM: SVM: Add KVM_SEV SEND_START command") Fixes: d3d1af85e2c75 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command") Fixes: eba04b20e4861 ("KVM: x86: Account a variety of miscellaneous allocations") Signed-off-by: Ashish Kalra ashish.kalra@amd.com --- arch/x86/kvm/svm/sev.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 7c392873626f..4b7d490c0b63 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -688,7 +688,7 @@ static int sev_launch_measure(struct kvm *kvm, struct kvm_sev_cmd *argp) if (params.len > SEV_FW_BLOB_MAX_SIZE) return -EINVAL;

- blob = kmalloc(params.len, GFP_KERNEL_ACCOUNT); + blob = kzalloc(params.len, GFP_KERNEL_ACCOUNT); if (!blob) return -ENOMEM;

@@ -808,7 +808,7 @@ static int __sev_dbg_decrypt_user(struct kvm *kvm, unsigned long paddr, if (!IS_ALIGNED(dst_paddr, 16) || !IS_ALIGNED(paddr, 16) || !IS_ALIGNED(size, 16)) { - tpage = (void *)alloc_page(GFP_KERNEL); + tpage = (void *)alloc_page(GFP_KERNEL | __GFP_ZERO); if (!tpage) return -ENOMEM;

@@ -1094,7 +1094,7 @@ static int sev_get_attestation_report(struct kvm *kvm, struct kvm_sev_cmd *argp) if (params.len > SEV_FW_BLOB_MAX_SIZE) return -EINVAL;

- blob = kmalloc(params.len, GFP_KERNEL_ACCOUNT); + blob = kzalloc(params.len, GFP_KERNEL_ACCOUNT); if (!blob) return -ENOMEM;

@@ -1176,7 +1176,7 @@ static int sev_send_start(struct kvm *kvm, struct kvm_sev_cmd *argp) return -EINVAL;

/* allocate the memory to hold the session data blob */ - session_data = kmalloc(params.session_len, GFP_KERNEL_ACCOUNT); + session_data = kzalloc(params.session_len, GFP_KERNEL_ACCOUNT); if (!session_data) return -ENOMEM;

@@ -1300,11 +1300,11 @@ static int sev_send_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)

/* allocate memory for header and transport buffer */ ret = -ENOMEM; - hdr = kmalloc(params.hdr_len, GFP_KERNEL_ACCOUNT); + hdr = kzalloc(params.hdr_len, GFP_KERNEL_ACCOUNT); if (!hdr) goto e_unpin;

- trans_data = kmalloc(params.trans_len, GFP_KERNEL_ACCOUNT); + trans_data = kzalloc(params.trans_len, GFP_KERNEL_ACCOUNT); if (!trans_data) goto e_free_hdr;