And of course, I forgot to add Hugh ;) Fix that.
On 04/28, Oleg Nesterov wrote:
>
> valid_vma() rejects the VM_SHARED vmas, but this still allows to insert
> a probe into the MAP_SHARED but not VM_MAYWRITE vma.
>
> Currently this is fine, such a mapping doesn't really differ from the
> private read-only mmap except mprotect(PROT_WRITE) won't work. However,
> get_user_pages(FOLL_WRITE | FOLL_FORCE) doesn't allow to COW in this
> case, and it would be safer to follow the same conventions as mm even
> if currently this happens to work.
>
> After the recent cda540ace6a1 "mm: get_user_pages(write,force) refuse
> to COW in shared areas" only uprobes can insert an anon page into the
> shared file-backed area, lets stop this and change valid_vma() to check
> VM_MAYSHARE instead.
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
> ---
> kernel/events/uprobes.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index d1edc5e..7716c40 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -127,7 +127,7 @@ struct xol_area {
> */
> static bool valid_vma(struct vm_area_struct *vma, bool is_register)
> {
> - vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED;
> + vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE;
>
> if (is_register)
> flags |= VM_WRITE;
> --
> 1.5.5.1
>
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