From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xen.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
Jan Beulich <JBeulich@suse.com>
Subject: [PATCH] x86/pv: Prohibit attempts to initialise a vcpu with EFLAGS.{NT, VM} set
Date: Thu, 31 Aug 2017 18:07:26 +0100 [thread overview]
Message-ID: <1504199246-5084-1-git-send-email-andrew.cooper3@citrix.com> (raw)
Luckily, this isn't a security issue, because the fix for XSA-202 (c/s
0e47f92b072) took a proactive aproach and clobbered these flags on the
exit-to-guest path.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
---
xen/arch/x86/domain.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index dbddc53..ced1d2e 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -765,7 +765,8 @@ int arch_set_info_guest(
!is_canonical_address(c.nat->gs_base_user) ||
!is_canonical_address(c.nat->event_callback_eip) ||
!is_canonical_address(c.nat->syscall_callback_eip) ||
- !is_canonical_address(c.nat->failsafe_callback_eip) )
+ !is_canonical_address(c.nat->failsafe_callback_eip) ||
+ (c.nat->user_regs.rflags & (X86_EFLAGS_NT|X86_EFLAGS_VM)) )
return -EINVAL;
fixup_guest_stack_selector(d, c.nat->user_regs.ss);
@@ -784,6 +785,9 @@ int arch_set_info_guest(
}
else
{
+ if ( c.nat->user_regs.eflags & (X86_EFLAGS_NT|X86_EFLAGS_VM) )
+ return -EINVAL;
+
fixup_guest_stack_selector(d, c.cmp->user_regs.ss);
fixup_guest_stack_selector(d, c.cmp->kernel_ss);
fixup_guest_code_selector(d, c.cmp->user_regs.cs);
--
2.1.4
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next reply other threads:[~2017-08-31 17:07 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-31 17:07 Andrew Cooper [this message]
2017-09-01 8:45 ` [PATCH] x86/pv: Prohibit attempts to initialise a vcpu with EFLAGS.{NT, VM} set Jan Beulich
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