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Commit df279ca8 authored by Renaud Lottiaux's avatar Renaud Lottiaux Committed by Linus Torvalds
Browse files

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: default avatarRenaud Lottiaux <renaud.lottiaux@kerlabs.com>
Signed-off-by: default avatarLouis Rilling <louis.rilling@kerlabs.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus 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;