linux-kernel - [PATCH 3.16 41/87] kernel/signal.c: trace_signal_deliver when signal_group

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Message-ID: <lsq.1570043211.293301169@decadent.org.uk>
Date:   Wed, 02 Oct 2019 20:06:51 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Oleg Nesterov" <oleg@...hat.com>,
        "Ivan Delalande" <colona@...sta.com>,
        "Zhenliang Wei" <weizhenliang@...wei.com>,
        "Deepa Dinamani" <deepa.kernel@...il.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Arnd Bergmann" <arnd@...db.de>,
        "Christian Brauner" <christian@...uner.io>
Subject: [PATCH 3.16 41/87] kernel/signal.c: trace_signal_deliver when
 signal_group_exit

3.16.75-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Zhenliang Wei <weizhenliang@...wei.com>

commit 98af37d624ed8c83f1953b1b6b2f6866011fc064 upstream.

In the fixes commit, removing SIGKILL from each thread signal mask and
executing "goto fatal" directly will skip the call to
"trace_signal_deliver".  At this point, the delivery tracking of the
SIGKILL signal will be inaccurate.

Therefore, we need to add trace_signal_deliver before "goto fatal" after
executing sigdelset.

Note: SEND_SIG_NOINFO matches the fact that SIGKILL doesn't have any info.

Link: http://lkml.kernel.org/r/20190425025812.91424-1-weizhenliang@huawei.com
Fixes: cf43a757fd4944 ("signal: Restore the stop PTRACE_EVENT_EXIT")
Signed-off-by: Zhenliang Wei <weizhenliang@...wei.com>
Reviewed-by: Christian Brauner <christian@...uner.io>
Reviewed-by: Oleg Nesterov <oleg@...hat.com>
Cc: Eric W. Biederman <ebiederm@...ssion.com>
Cc: Ivan Delalande <colona@...sta.com>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Deepa Dinamani <deepa.kernel@...il.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 kernel/signal.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2277,6 +2277,8 @@ relock:
 	if (signal_group_exit(signal)) {
 		ksig->info.si_signo = signr = SIGKILL;
 		sigdelset(&current->pending.signal, SIGKILL);
+		trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
+				&sighand->action[SIGKILL - 1]);
 		recalc_sigpending();
 		goto fatal;
 	}