Messages in this thread Patch in this message | | | Date | Sat, 18 Sep 2021 10:31:20 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] Modify the check condition |
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On Sat, Sep 18, 2021 at 06:52:32AM +0000, cgel.zte@gmail.com wrote: > From: Yang Guang <yang.guang5@zte.com.cn> > > The vma may be NULL, and accessing the member of vma like "vma->vm_start" > in calling follow_phys may occur segmentation fault. > So it should check vma at beginning. If vma is null, it will return. And > the if condition won't execute "vm->vm_flags". > > Signed-off-by: Yang Guang <yang.guang5@zte.com.cn> > --- > arch/x86/mm/pat/memtype.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c > index 4ba2a3ee4bce..b7108b37b754 100644 > --- a/arch/x86/mm/pat/memtype.c > +++ b/arch/x86/mm/pat/memtype.c > @@ -1089,7 +1089,7 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, > resource_size_t paddr; > unsigned long prot; > > - if (vma && !(vma->vm_flags & VM_PAT)) > + if (!(vma) || !(vma->vm_flags & VM_PAT)) > return;
Yet another braindead patch that shows you don't actually understand C.
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