From df279ca8966c3de83105428e3391ab17690802a9 Mon Sep 17 00:00:00 2001
From: Renaud Lottiaux <renaud.lottiaux@kerlabs.com>
Date: Tue, 30 Jun 2009 11:41:34 -0700
Subject: [PATCH] bsdacct: fix access to invalid filp in acct_on()
The file opened in acct_on and freshly stored in the ns->bacct struct can
be closed in acct_file_reopen by a concurrent call after we release
acct_lock and before we call mntput(file->f_path.mnt).
Record file->f_path.mnt in a local variable and use this variable only.
Signed-off-by: Renaud Lottiaux <renaud.lottiaux@kerlabs.com>
Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/acct.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/acct.c b/kernel/acct.c
index 7afa31564162..9f3391090b3e 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -215,6 +215,7 @@ static void acct_file_reopen(struct bsd_acct_struct *acct, struct file *file,
static int acct_on(char *name)
{
struct file *file;
+ struct vfsmount *mnt;
int error;
struct pid_namespace *ns;
struct bsd_acct_struct *acct = NULL;
@@ -256,11 +257,12 @@ static int acct_on(char *name)
acct = NULL;
}
- mnt_pin(file->f_path.mnt);
+ mnt = file->f_path.mnt;
+ mnt_pin(mnt);
acct_file_reopen(ns->bacct, file, ns);
spin_unlock(&acct_lock);
- mntput(file->f_path.mnt); /* it's pinned, now give up active reference */
+ mntput(mnt); /* it's pinned, now give up active reference */
kfree(acct);
return 0;
--
2.20.1