Re: [PATCH] audit: fix audit_exe_compare using get_mm_exe_file

Fix original naive attempt to get/lock access to task->mm->exe_file by using get_mm_exe_file and checking for NULL. See: https://lkml.org/lkml/2016/7/30/97 Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; --- kernel/audit_watch.c | 13 ++++++++++--- 1 files changed, 10 insertions(+), 3 deletions(-) diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c index d6709eb..0b29279 100644 --- a/kernel/audit_watch.c +++ b/kernel/audit_watch.c @@ -19,6 +19,7 @@ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ +#include <linux/file.h> #include <linux/kernel.h> #include <linux/audit.h> #include <linux/kthread.h> @@ -540,14 +541,20 @@ int audit_dupe_exe(struct audit_krule *new, struct audit_krule *old) int audit_exe_compare(struct task_struct *tsk, struct audit_fsnotify_mark *mark) { + struct mm_struct *mm; struct file *exe_file; unsigned long ino; dev_t dev; - rcu_read_lock(); - exe_file = rcu_dereference(tsk->mm->exe_file); + mm = get_task_mm(tsk); + if (!mm) + return 0; + exe_file = get_mm_exe_file(mm); + mmput(mm); + if (!exe_file) + return 0; ino = exe_file->f_inode->i_ino; dev = exe_file->f_inode->i_sb->s_dev; - rcu_read_unlock(); + fput(exe_file); return audit_mark_compare(mark, ino, dev); }