[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20220201180822.970781574@linuxfoundation.org>
Date: Tue, 1 Feb 2022 19:16:49 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
"stable@...r.kernel.org, Guillaume Bertholon"
<guillaume.bertholon@....fr>,
Guillaume Bertholon <guillaume.bertholon@....fr>
Subject: [PATCH 4.4 25/25] KVM: x86: Fix misplaced backport of "work around leak of uninitialized stack contents"
From: Guillaume Bertholon <guillaume.bertholon@....fr>
The upstream commit 541ab2aeb282 ("KVM: x86: work around leak of
uninitialized stack contents") resets `exception` in the function
`kvm_write_guest_virt_system`.
However, its backported version in stable (commit ba7f1c934f2e
("KVM: x86: work around leak of uninitialized stack contents")) applied
the change in `emulator_write_std` instead.
This patch moves the memset instruction back to
`kvm_write_guest_virt_system`.
Fixes: ba7f1c934f2e ("KVM: x86: work around leak of uninitialized stack contents")
Signed-off-by: Guillaume Bertholon <guillaume.bertholon@....fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/x86/kvm/x86.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4417,13 +4417,6 @@ static int emulator_write_std(struct x86
if (!system && kvm_x86_ops->get_cpl(vcpu) == 3)
access |= PFERR_USER_MASK;
- /*
- * FIXME: this should call handle_emulation_failure if X86EMUL_IO_NEEDED
- * is returned, but our callers are not ready for that and they blindly
- * call kvm_inject_page_fault. Ensure that they at least do not leak
- * uninitialized kernel stack memory into cr2 and error code.
- */
- memset(exception, 0, sizeof(*exception));
return kvm_write_guest_virt_helper(addr, val, bytes, vcpu,
access, exception);
}
@@ -4431,6 +4424,13 @@ static int emulator_write_std(struct x86
int kvm_write_guest_virt_system(struct kvm_vcpu *vcpu, gva_t addr, void *val,
unsigned int bytes, struct x86_exception *exception)
{
+ /*
+ * FIXME: this should call handle_emulation_failure if X86EMUL_IO_NEEDED
+ * is returned, but our callers are not ready for that and they blindly
+ * call kvm_inject_page_fault. Ensure that they at least do not leak
+ * uninitialized kernel stack memory into cr2 and error code.
+ */
+ memset(exception, 0, sizeof(*exception));
return kvm_write_guest_virt_helper(addr, val, bytes, vcpu,
PFERR_WRITE_MASK, exception);
}
Powered by blists - more mailing lists