linux-kernel - [PATCH 3/3] get_signal: don't initialize ksig->info if SIGNAL_GROUP_EXIT/group_exec

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Date: Mon, 26 Feb 2024 17:56:53 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>,
	Christian Brauner <brauner@...nel.org>,
	Peter Collingbourne <pcc@...gle.com>,
	Wen Yang <wenyang.linux@...mail.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] get_signal: don't initialize ksig->info if
 SIGNAL_GROUP_EXIT/group_exec_task

This initialization is incomplete and unnecessary, neither do_group_exit()
nor PF_USER_WORKER need ksig->info.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/signal.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index a69d3069067a..9c6a5ccac328 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2727,12 +2727,15 @@ bool get_signal(struct ksignal *ksig)
 		/* Has this task already been marked for death? */
 		if ((signal->flags & SIGNAL_GROUP_EXIT) ||
 		     signal->group_exec_task) {
-			clear_siginfo(&ksig->info);
-			ksig->info.si_signo = signr = SIGKILL;
+			signr = SIGKILL;
 			sigdelset(&current->pending.signal, SIGKILL);
 			trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
-				&sighand->action[SIGKILL - 1]);
+					     &sighand->action[SIGKILL-1]);
 			recalc_sigpending();
+			/*
+			 * implies do_group_exit() or return to PF_USER_WORKER,
+			 * no need to initialize ksig->info/etc.
+			 */
 			goto fatal;
 		}
 
-- 
2.25.1.362.g51ebf55