audit: fix exe_file access in audit_exe_compare

Prior to the change the function would blindly deference mm, exe_file
and exe_file->f_inode, each of which could have been NULL or freed.

Use get_task_exe_file to safely obtain stable exe_file.

Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
Acked-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Richard Guy Briggs <rgb@redhat.com>
Cc: <stable@vger.kernel.org> # 4.3.x
Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Mateusz Guzik 2016-08-23 16:20:39 +02:00 committed by Paul Moore
parent cd81a9170e
commit 5efc244346

View File

@ -19,6 +19,7 @@
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/ */
#include <linux/file.h>
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/audit.h> #include <linux/audit.h>
#include <linux/kthread.h> #include <linux/kthread.h>
@ -544,10 +545,11 @@ int audit_exe_compare(struct task_struct *tsk, struct audit_fsnotify_mark *mark)
unsigned long ino; unsigned long ino;
dev_t dev; dev_t dev;
rcu_read_lock(); exe_file = get_task_exe_file(tsk);
exe_file = rcu_dereference(tsk->mm->exe_file); if (!exe_file)
return 0;
ino = exe_file->f_inode->i_ino; ino = exe_file->f_inode->i_ino;
dev = exe_file->f_inode->i_sb->s_dev; dev = exe_file->f_inode->i_sb->s_dev;
rcu_read_unlock(); fput(exe_file);
return audit_mark_compare(mark, ino, dev); return audit_mark_compare(mark, ino, dev);
} }