On Wed, 14 May 2014 16:01:22 -0700 Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> 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 sentence is the best part of the changelog! People often do this
- they put all the good stuff after the ^---. I always move it into
the changelog.
So how old is this bug?
> --- 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};
nit: this could be local to arch_setup_additional_pages().
> /* 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);
--
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