Messages in this thread | | | Date | Thu, 18 Apr 2024 20:18:21 +0200 | From | Oleg Nesterov <> | Subject | Re: [patch V2 26/50] signal: Get rid of resched_timer logic |
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On 04/18, Oleg Nesterov wrote: > > On 04/11, Thomas Gleixner wrote: > > > > There is no reason for handing the *resched pointer argument through > > several functions just to check whether the signal is related to a self > > rearming posix timer. > > Agreed, these changes looks good to me.
I meant the intent.
But this is not simple, collect_signal() checks SIGQUEUE_PREALLOC exactly because (iiuc) we need to ensure that SI_TIMER didn't come from userspace.
perhaps we should disallow SI_TIMER with _sys_private != 0 from userspace, I dunno...
And I don't really understand the "not to be passed to user" comment in include/uapi/asm-generic/siginfo.h. copy_siginfo_to_user() just copies the whole kernel_siginfo.
Confused.
> But, > > > SI_TIMER is only used by the posix timer code and cannot be queued from > > user space. > > Why? I think sigqueueinfo() can certainly use si_code = SI_TIMER, so > > > @@ -1011,6 +1001,9 @@ static int __send_signal_locked(int sig, > > > > lockdep_assert_held(&t->sighand->siglock); > > > > + if (WARN_ON_ONCE(!is_si_special(info) && info->si_code == SI_TIMER)) > > + return 0; > > this can be easily triggered by userspace and thus looks wrong. > > Oleg.
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