linux-kernel - [PATCH 3/9] KVM: x86: Loading segments on 64-bit mode may be wrong

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon,  2 Jun 2014 18:34:05 +0300
From:	Nadav Amit <namit@...technion.ac.il>
To:	pbonzini@...hat.com
Cc:	gleb@...nel.org, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Nadav Amit <namit@...technion.ac.il>
Subject: [PATCH 3/9] KVM: x86: Loading segments on 64-bit mode may be wrong

The current emulator implementation ignores the high 32 bits of the base in
long-mode.  During segment load from the LDT, the base of the LDT is calculated
incorrectly and may cause the wrong segment to be loaded.

Signed-off-by: Nadav Amit <namit@...technion.ac.il>
---
 arch/x86/kvm/emulate.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 136088f..7e4a45c 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1358,17 +1358,19 @@ static void get_descriptor_table_ptr(struct x86_emulate_ctxt *ctxt,
 				     u16 selector, struct desc_ptr *dt)
 {
 	const struct x86_emulate_ops *ops = ctxt->ops;
+	u32 base3 = 0;
 
 	if (selector & 1 << 2) {
 		struct desc_struct desc;
 		u16 sel;
 
 		memset (dt, 0, sizeof *dt);
-		if (!ops->get_segment(ctxt, &sel, &desc, NULL, VCPU_SREG_LDTR))
+		if (!ops->get_segment(ctxt, &sel, &desc, &base3,
+				      VCPU_SREG_LDTR))
 			return;
 
 		dt->size = desc_limit_scaled(&desc); /* what if limit > 65535? */
-		dt->address = get_desc_base(&desc);
+		dt->address = get_desc_base(&desc) | ((u64)base3 << 32);
 	} else
 		ops->get_gdt(ctxt, dt);
 }
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/