linux-kernel - [ 088/187] mm: correctly synchronize rss-counters at exit/exec

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]

Date:	Thu, 12 Jul 2012 15:34:04 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Markus Trippelsdorf <markus@...ppelsdorf.de>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	Oleg Nesterov <oleg@...hat.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Hugh Dickins <hughd@...gle.com>
Subject: [ 088/187] mm: correctly synchronize rss-counters at exit/exec

From: Greg KH <gregkh@...uxfoundation.org>

3.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Konstantin Khlebnikov <khlebnikov@...nvz.org>

commit 4fe7efdbdfb1c7e7a7f31decfd831c0f31d37091 upstream.

do_exit() and exec_mmap() call sync_mm_rss() before mm_release() does
put_user(clear_child_tid) which can update task->rss_stat and thus make
mm->rss_stat inconsistent.  This triggers the "BUG:" printk in check_mm().

Let's fix this bug in the safest way, and optimize/cleanup this later.

Reported-by: Markus Trippelsdorf <markus@...ppelsdorf.de>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@...nvz.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: Hugh Dickins <hughd@...gle.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/exec.c     |    2 +-
 kernel/exit.c |    1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -823,10 +823,10 @@ static int exec_mmap(struct mm_struct *m
 	/* Notify parent that we're no longer interested in the old VM */
 	tsk = current;
 	old_mm = current->mm;
-	sync_mm_rss(old_mm);
 	mm_release(tsk, old_mm);
 
 	if (old_mm) {
+		sync_mm_rss(old_mm);
 		/*
 		 * Make sure that if there is a core dump in progress
 		 * for the old mm, we get out and die instead of going
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -643,6 +643,7 @@ static void exit_mm(struct task_struct *
 	mm_release(tsk, mm);
 	if (!mm)
 		return;
+	sync_mm_rss(mm);
 	/*
 	 * Serialize with any possible pending coredump.
 	 * We must hold mmap_sem around checking core_state


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/