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

在 2025/2/20 0:12, David Hildenbrand 写道:

On 19.02.25 16:22, Oleg Nesterov wrote:

quoted

On 02/18, Tong Tiangen wrote:

quoted

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.