From df279ca8966c3de83105428e3391ab17690802a9 Mon Sep 17 00:00:00 2001 From: Renaud Lottiaux 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 Signed-off-by: Louis Rilling Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/acct.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/acct.c b/kernel/acct.c index 7afa3156416..9f3391090b3 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;