[PATCH 3.15] x86,vdso: Fix an OOPS accessing the hpet mapping w/o an hpet

[Andy Lutomirski]

The access should fail, but it shouldn't oops.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
---

The oops can be triggered in qemu using -no-hpet (but not nohpet) by
running a 32-bit program and reading a couple of pages before the vdso.

This will conflict with tip/x86/vdso.  Sorry.

 arch/x86/vdso/vdso32-setup.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index 0034898..33426da 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -147,6 +147,8 @@ int __init sysenter_setup(void)
 	return 0;
 }
 
+static struct page *no_pages[] = {NULL};
+
 /* Setup a VMA at program startup for the vsyscall page */
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
@@ -192,7 +194,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 			addr -  VDSO_OFFSET(VDSO_PREV_PAGES),
 			VDSO_OFFSET(VDSO_PREV_PAGES),
 			VM_READ,
-			NULL);
+			no_pages);
 
 	if (IS_ERR(vma)) {
 		ret = PTR_ERR(vma);
-- 
1.9.0

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