On Sun, Jul 14, 2019 at 03:02:06PM +0300, Dmitry V. Levin wrote:
> The introduction of clone3 syscall accidentally broke CLONE_PIDFD
> support in traditional clone syscall on compat x86 and those
> architectures that use do_fork to implement clone syscall.
>
> This bug was found by strace test suite.
>
> Link: https://strace.io/logs/strace/2019-07-12
> Fixes: 7f192e3cd316 ("fork: add clone3")
> Bisected-and-tested-by: Anatoly Pugachev <[email protected]>
> Signed-off-by: Dmitry V. Levin <[email protected]>
Good catch! Thank you Dmitry.
One change request below.
> ---
> arch/x86/ia32/sys_ia32.c | 1 +
> kernel/fork.c | 1 +
> 2 files changed, 2 insertions(+)
>
> diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c
> index 64a6c952091e..98754baf411a 100644
> --- a/arch/x86/ia32/sys_ia32.c
> +++ b/arch/x86/ia32/sys_ia32.c
> @@ -239,6 +239,7 @@ COMPAT_SYSCALL_DEFINE5(x86_clone, unsigned long,
> clone_flags,
> {
> struct kernel_clone_args args = {
> .flags = (clone_flags & ~CSIGNAL),
> + .pidfd = parent_tidptr,
> .child_tid = child_tidptr,
> .parent_tid = parent_tidptr,
> .exit_signal = (clone_flags & CSIGNAL),
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 8f3e2d97d771..2c3cbad807b6 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -2417,6 +2417,7 @@ long do_fork(unsigned long clone_flags,
> {
> struct kernel_clone_args args = {
> .flags = (clone_flags & ~CSIGNAL),
> + .pidfd = parent_tidptr,
> .child_tid = child_tidptr,
> .parent_tid = parent_tidptr,
> .exit_signal = (clone_flags & CSIGNAL),
> --
Both of these legacy clone helpers need to make CLONE_PIDFD and
CLONE_PARENT_SETTID incompatible, i.e. could you please add a helper to
kernel/fork.c:
bool legacy_clone_args_valid(const struct kernel_clone_args *kargs)
{
/* clone(CLONE_PIDFD) uses parent_tidptr to return a pidfd */
if ((kargs->flags & CLONE_PIDFD) && (kargs->flags &
CLONE_PARENT_SETTID))
return false;
}
and export it and use it in ia32 too?
Then resend and I'll put it into my tree that already has a few other
fixes about to be sent.
Christian
