99cbc7
From bcaa73c80a8634c7db6e7b3a90f2f56b0817bfc5 Mon Sep 17 00:00:00 2001
99cbc7
Message-Id: <bcaa73c80a8634c7db6e7b3a90f2f56b0817bfc5@dist-git>
99cbc7
From: Michal Privoznik <mprivozn@redhat.com>
99cbc7
Date: Thu, 7 Mar 2019 14:17:01 +0100
99cbc7
Subject: [PATCH] cpu: Don't access invalid memory in virCPUx86Translate
99cbc7
MIME-Version: 1.0
99cbc7
Content-Type: text/plain; charset=UTF-8
99cbc7
Content-Transfer-Encoding: 8bit
99cbc7
99cbc7
Problem is that if there are no signatures for a CPU, then we
99cbc7
still allocate cpu->signatures (even though with size 0). Later,
99cbc7
we access cpu->signatures[0] if cpu->signatures is not NULL.
99cbc7
99cbc7
 Invalid read of size 4
99cbc7
    at 0x5F439D7: virCPUx86Translate (cpu_x86.c:2930)
99cbc7
    by 0x5F3C239: virCPUTranslate (cpu.c:927)
99cbc7
    by 0x57CE7A1: qemuProcessUpdateGuestCPU (qemu_process.c:5870)
99cbc7
    ...
99cbc7
  Address 0xf752d40 is 0 bytes after a block of size 0 alloc'd
99cbc7
    at 0x4C30EC6: calloc (vg_replace_malloc.c:711)
99cbc7
    by 0x5DBDE4E: virAllocN (viralloc.c:190)
99cbc7
    by 0x5F3E4FA: x86ModelCopySignatures (cpu_x86.c:990)
99cbc7
    by 0x5F3E60F: x86ModelCopy (cpu_x86.c:1008)
99cbc7
    by 0x5F3E7CB: x86ModelFromCPU (cpu_x86.c:1068)
99cbc7
    by 0x5F4397E: virCPUx86Translate (cpu_x86.c:2922)
99cbc7
    by 0x5F3C239: virCPUTranslate (cpu.c:927)
99cbc7
    by 0x57CE7A1: qemuProcessUpdateGuestCPU (qemu_process.c:5870)
99cbc7
    ...
99cbc7
99cbc7
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
99cbc7
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
99cbc7
(cherry picked from commit 62cb9c335c43a722e81ac0a1ed6e1111ba1d428b)
99cbc7
99cbc7
https://bugzilla.redhat.com/show_bug.cgi?id=1558558
99cbc7
https://bugzilla.redhat.com/show_bug.cgi?id=1687515
99cbc7
99cbc7
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
99cbc7
Reviewed-by: Ján Tomko <jtomko@redhat.com>
99cbc7
---
99cbc7
 src/cpu/cpu_x86.c | 3 +++
99cbc7
 1 file changed, 3 insertions(+)
99cbc7
99cbc7
diff --git a/src/cpu/cpu_x86.c b/src/cpu/cpu_x86.c
99cbc7
index f6844aaa0d..466c79031d 100644
99cbc7
--- a/src/cpu/cpu_x86.c
99cbc7
+++ b/src/cpu/cpu_x86.c
99cbc7
@@ -1021,6 +1021,9 @@ x86ModelCopySignatures(virCPUx86ModelPtr dst,
99cbc7
 {
99cbc7
     size_t i;
99cbc7
 
99cbc7
+    if (src->nsignatures == 0)
99cbc7
+        return 0;
99cbc7
+
99cbc7
     if (VIR_ALLOC_N(dst->signatures, src->nsignatures) < 0)
99cbc7
         return -1;
99cbc7
 
99cbc7
-- 
99cbc7
2.21.0
99cbc7