Commit 0a1eb2d4 authored Sep 30, 2016 by Andy Lutomirski Committed by Ingo Molnar Oct 20, 2016

fs/proc: Stop reporting eip and esp in /proc/PID/stat



Reporting these fields on a non-current task is dangerous.  If the
task is in any state other than normal kernel code, they may contain
garbage or even kernel addresses on some architectures.  (x86_64
used to do this.  I bet lots of architectures still do.)  With
CONFIG_THREAD_INFO_IN_TASK=y, it can OOPS, too.

As far as I know, there are no use programs that make any material
use of these fields, so just get rid of them.

Reported-by: Jann Horn <jann@thejh.net>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux API <linux-api@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Tycho Andersen <tycho.andersen@canonical.com>
Link: http://lkml.kernel.org/r/a5fed4c3f4e33ed25d4bb03567e329bc5a712bcc.1475257877.git.luto@kernel.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 137baabe

fs/proc/array.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -412,10 +412,11 @@ static int do_task_stat(struct seq_file m, struct pid_namespace ns,
		mm = get_task_mm(task);
		if (mm) {
		vsize = task_vsize(mm);
		if (permitted) {
		eip = KSTK_EIP(task);
		esp = KSTK_ESP(task);
		}
		/*
		* esp and eip are intentionally zeroed out. There is no
		* non-racy way to read them without freezing the task.
		* Programs that need reliable values can use ptrace(2).
		*/
		}

		get_task_comm(tcomm, task);