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KVM: SVM: Use kzalloc for sev ioctl interfaces to prevent kernel data leak

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commit d22d2474e3953996f03528b84b7f52cc26a39403 upstream.

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>
Reviewed-by: Peter Gonda <pgonda@google.com>
Message-Id: <20220516154310.3685678-1-Ashish.Kalra@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ashish Kalra 2022-05-16 15:43:10 +00:00 committed by Greg Kroah-Hartman
parent d6be031a2f
commit 401bef1f95
1 changed files with 2 additions and 2 deletions
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4
arch/x86/kvm/svm/sev.c
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@ -537,7 +537,7 @@ static int sev_launch_measure(struct kvm *kvm, struct kvm_sev_cmd *argp)
}
ret = -ENOMEM;
blob = kmalloc(params.len, GFP_KERNEL_ACCOUNT);
blob = kzalloc(params.len, GFP_KERNEL_ACCOUNT);
if (!blob)
goto e_free;
@ -676,7 +676,7 @@ 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;