Re: Add Morton,Peter and David for discussion//Re: [PATCH -next] uprobes: fix two zero old_folio bugs in __replace_page()

[Tong Tiangen]

在 2025/2/20 0:12, David Hildenbrand 写道:
> On 19.02.25 16:22, Oleg Nesterov wrote:
> > On 02/18, Tong Tiangen wrote:
> > > OK, Before your rewrite last merged, How about i change the solution to
> > > just reject them immediately after get_user_page_vma_remote()？
> >
> > I agree, uprobe_write_opcode() should simply fail if 
> > is_zero_page(old_page).
>
> Yes. That's currently only syzkaller that triggers it, not some sane use 
> case.

OK, change as follows:

--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -506,6 +506,12 @@ int uprobe_write_opcode(struct arch_uprobe 
*auprobe, struct mm_struct *mm,
        if (ret <= 0)
                goto put_old;

+       if (WARN(is_zero_page(old_page),
+                "uprobe should never work on zero page\n")) {
+               ret = -EINVAL;
+               goto put_old;
+       }
+
        if (WARN(!is_register && PageCompound(old_page),
                 "uprobe unregister should never work on compound 
page\n")) {
                ret = -EINVAL;

If ok, i will send v2 soon.

Thanks,
Tong.

>