linux-kernel - [RFC][PATCHv2 6/8] kexec: switch to printk.emergency mode in unsafe places

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20170329092511.3958-7-sergey.senozhatsky@gmail.com>
Date:   Wed, 29 Mar 2017 18:25:09 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Petr Mladek <pmladek@...e.com>
Cc:     Jan Kara <jack@...e.cz>, Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Eric Biederman <ebiederm@...ssion.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Pavel Machek <pavel@....cz>,
        Len Brown <len.brown@...el.com>, linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: [RFC][PATCHv2 6/8] kexec: switch to printk.emergency mode in unsafe places

Switch to printk emergency mode in kernel_kexec(), this
lets us to immediately flush pending kernel message to
the console and to avoid potentially unsafe calls into
the scheduler.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
---
 kernel/kexec_core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index bfe62d5b3872..5684ba36ec15 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1496,6 +1496,8 @@ int kernel_kexec(void)
 		goto Unlock;
 	}
 
+	printk_emergency_begin();
+
 #ifdef CONFIG_KEXEC_JUMP
 	if (kexec_image->preserve_context) {
 		lock_system_sleep();
@@ -1565,6 +1567,8 @@ int kernel_kexec(void)
 	}
 #endif
 
+	printk_emergency_end();
+
  Unlock:
 	mutex_unlock(&kexec_mutex);
 	return error;
-- 
2.12.2