fix segment_base() to properly check for null segment selector and
avoid accessing NULL pointer if ldt selector in null.
Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 558eb9a..49f5c7b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -229,7 +229,7 @@ unsigned long segment_base(u16 selector)
unsigned long table_base;
unsigned long v;
- if (selector == 0)
+ if (!(selector & ~3))
return 0;
native_store_gdt(&gdt);
@@ -238,6 +238,8 @@ unsigned long segment_base(u16 selector)
if (selector & 4) { /* from ldt */
u16 ldt_selector = kvm_read_ldt();
+ if (!(ldt_selector & ~3))
+ return 0;
table_base = segment_base(ldt_selector);
}
d = (struct desc_struct *)(table_base + (selector & ~7));
--
1.6.5
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