Commit 696db303 authored by Maxim Levitsky's avatar Maxim Levitsky Committed by Paolo Bonzini
Browse files

KVM: x86: smm: number of GPRs in the SMRAM image depends on the image format 



On 64 bit host, if the guest doesn't have X86_FEATURE_LM, KVM will
access 16 gprs to 32-bit smram image, causing out-ouf-bound ram
access.

On 32 bit host, the rsm_load_state_64/enter_smm_save_state_64
is compiled out, thus access overflow can't happen.

Fixes: b443183a ("KVM: x86: Reduce the number of emulator GPRs to '8' for 32-bit KVM")

Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20221025124741.228045-15-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ad8f9e69

arch/x86/kvm/emulate.c

+2 −2
Original line number Diff line number Diff line
@@ -2461,7 +2461,7 @@ static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt, 
	ctxt->eflags =             GET_SMSTATE(u32, smstate, 0x7ff4) | X86_EFLAGS_FIXED;

	ctxt->_eip =               GET_SMSTATE(u32, smstate, 0x7ff0);



	for (i = 0; i < NR_EMULATOR_GPRS; i++)

	for (i = 0; i < 8; i++)

		*reg_write(ctxt, i) = GET_SMSTATE(u32, smstate, 0x7fd0 + i * 4);



	val = GET_SMSTATE(u32, smstate, 0x7fcc);
@@ -2518,7 +2518,7 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt, 
	u16 selector;

	int i, r;



	for (i = 0; i < NR_EMULATOR_GPRS; i++)

	for (i = 0; i < 16; i++)

		*reg_write(ctxt, i) = GET_SMSTATE(u64, smstate, 0x7ff8 - i * 8);



	ctxt->_eip   = GET_SMSTATE(u64, smstate, 0x7f78);