Messages in this thread | | | Date | Wed, 19 Aug 2020 11:04:24 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] mm/migrate: Avoid possible unnecessary ptrace_may_access() call in kernel_move_pages() |
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On Mon, Aug 17, 2020 at 07:59:33AM -0400, Miaohe Lin wrote: > There is no need to check if this process has the right to modify the > specified process when they are same. > > Signed-off-by: Hongxiang Lou <louhongxiang@huawei.com> > Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> > --- > mm/migrate.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index 34a842a8eb6a..342c1ce0b433 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1903,7 +1903,7 @@ static int kernel_move_pages(pid_t pid, unsigned long nr_pages, > * Check if this process has the right to modify the specified > * process. Use the regular "ptrace_may_access()" checks. > */ > - if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) { > + if (pid && !ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) { > rcu_read_unlock(); > err = -EPERM; > goto out;
NAK, please don't do this -- the ptrace and security hooks already do these kinds of self-introspection checks, and I'd like to keep a central place to perform these kinds of checks.
Is there a specific problem you've encountered that this fixes?
-- Kees Cook
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