Commit df279ca8 authored Jun 30, 2009 by Renaud Lottiaux Committed by Linus Torvalds Jun 30, 2009

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>

parent b4f90189

kernel/acct.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -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;

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