On 12/24, Andrey Vagin wrote:
>
> signalfd should be called with the flag SFD_RAW for that.
>
> signalfd_siginfo is not full for siginfo with a negative si_code.
> copy_siginfo_to_user() is copied a full siginfo to user-space, if
> si_code is negative. signalfd_copyinfo() doesn't do that and can't be
> expanded, because it has not compatiable format with siginfo_t.
Yes, but otoh perhaps we should change (fix) signalfd_siginfo/copyinfo,
its "default" case makes no sense if si_code < 0.
> Another problem is that a constant __SI_* is removed from si_code.
OK, so you add the additional put_user(kinfo->si_code). Again, in
this case we can extend signalfd_siginfo perhaps...
Anyway, the patch doesn't look right.
> +static int signalfd_copy_raw_info(struct signalfd_siginfo __user *siginfo,
> + siginfo_t *kinfo)
> +{
> + siginfo_t *uinfo = (siginfo_t *) siginfo;
> + int err;
> +
> + BUILD_BUG_ON(sizeof(siginfo_t) != sizeof(struct signalfd_siginfo));
> +
> + err = __clear_user(uinfo, sizeof(*uinfo));
> + err |= copy_siginfo_to_user(uinfo, kinfo);
This probably needs copy_siginfo_to_user32() if is_compat_task...
> + err |= __put_user(kinfo->si_code, &uinfo->si_code);
__put_user() is not safe? This allows to write to the kernel memory.
> @@ -286,6 +308,11 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *,
> user_mask,
> O_RDWR | (flags & (O_CLOEXEC |
> O_NONBLOCK)));
> if (ufd < 0)
> kfree(ctx);
> + else if (flags & SFD_RAW) {
> + struct fd f = fdget(ufd);
> + f.file->f_flags |= flags & SFD_RAW;
Well, but this is racy. How we can know that fdget(ufd) still
points to the same file created by anon_inode_getfd? Not to
mention f.file can be NULL.
Another CLONE_FILES thread can do close() right after fd_install().
And it can also do dup3().
Oleg.
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