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Tue, 17 Mar 2026 07:38:56 -0700 (PDT) MIME-Version: 1.0 References: <20260316151956.563558-1-kartikey406@gmail.com> In-Reply-To: From: Deepanshu Kartikey Date: Tue, 17 Mar 2026 20:08:44 +0530 X-Gm-Features: AaiRm52NZLh2X_VTuxcK4EwzGSrL0Dh9qff93nA1P79so-bjnoyTbLsWb3ODk-8 Message-ID: Subject: Re: [PATCH -mm v2] do_notify_parent: sanitize the valid_signal() checks To: Oleg Nesterov Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 62907140013 X-Rspamd-Server: rspam08 X-Stat-Signature: i7gxo1bajtmhqf97qt6hctdxgu5a3opf X-HE-Tag: 1773758337-759741 X-HE-Meta: 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 0SPPppEt 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 17, 2026 at 7:28=E2=80=AFPM Oleg Nesterov wro= te: > > Now that kernel_clone() checks valid_signal(args->exit_signal), the "sig" > argument of do_notify_parent() must always be valid or we have a bug. > > However, do_notify_parent() only checks that sig !=3D -1 at the start, th= en > it does another valid_signal() check before __send_signal_locked(). > > This is confusing. Change do_notify_parent() to WARN and return early if > valid_signal(sig) is false. > > Signed-off-by: Oleg Nesterov > --- > kernel/signal.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/kernel/signal.c b/kernel/signal.c > index 86aad7badb9a..683ef92f7234 100644 > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -2171,7 +2171,8 @@ bool do_notify_parent(struct task_struct *tsk, int = sig) > bool autoreap =3D false; > u64 utime, stime; > > - WARN_ON_ONCE(sig =3D=3D -1); > + if (WARN_ON_ONCE(!valid_signal(sig))) > + return false; > > /* do_notify_parent_cldstop should have been called instead. */ > WARN_ON_ONCE(task_is_stopped_or_traced(tsk)); > @@ -2252,7 +2253,7 @@ bool do_notify_parent(struct task_struct *tsk, int = sig) > * Send with __send_signal as si_pid and si_uid are in the > * parent's namespaces. > */ > - if (valid_signal(sig) && sig) > + if (sig) > __send_signal_locked(sig, &info, tsk->parent, PIDTYPE_TGI= D, false); > __wake_up_parent(tsk, tsk->parent); > spin_unlock_irqrestore(&psig->siglock, flags); > -- > 2.52.0 > > Acked-by: Deepanshu Kartikey