kvm: svm: Fix gctx page leak on invalid inputs

Ensure that snp gctx page allocation is adequately deallocated on
failure during snp_launch_start.

Fixes: 136d8bc931c8 ("KVM: SEV: Add KVM_SEV_SNP_LAUNCH_START command")
CC: Sean Christopherson <seanjc@google.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@redhat.com>
CC: Borislav Petkov <bp@alien8.de>
CC: Dave Hansen <dave.hansen@linux.intel.com>
CC: Ashish Kalra <ashish.kalra@amd.com>
CC: Tom Lendacky <thomas.lendacky@amd.com>
CC: John Allen <john.allen@amd.com>
CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: "David S. Miller" <davem@davemloft.net>
CC: Michael Roth <michael.roth@amd.com>
CC: Luis Chamberlain <mcgrof@kernel.org>
CC: Russ Weight <russ.weight@linux.dev>
CC: Danilo Krummrich <dakr@redhat.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: "Rafael J. Wysocki" <rafael@kernel.org>
CC: Tianfei zhang <tianfei.zhang@intel.com>
CC: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Message-ID: <20241105010558.1266699-2-dionnaglaze@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 03c7db3b4cc37822d381fcbdd92ae9741b14f783..fb854cf20ac3be955e0c45412b45e607ec5e50e2 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2215,10 +2215,6 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
        if (sev->snp_context)
                return -EINVAL;
 
-       sev->snp_context = snp_context_create(kvm, argp);
-       if (!sev->snp_context)
-               return -ENOTTY;
-
        if (params.flags)
                return -EINVAL;
 
@@ -2233,6 +2229,10 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
        if (params.policy & SNP_POLICY_MASK_SINGLE_SOCKET)
                return -EINVAL;
 
+       sev->snp_context = snp_context_create(kvm, argp);
+       if (!sev->snp_context)
+               return -ENOTTY;
+
        start.gctx_paddr = __psp_pa(sev->snp_context);
        start.policy = params.policy;
        memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw));