diff options
author | Oleg Nesterov <oleg@redhat.com> | 2009-06-23 19:25:32 (GMT) |
---|---|---|
committer | James Morris <jmorris@namei.org> | 2009-08-10 10:47:42 (GMT) |
commit | 13f0feafa6b8aead57a2a328e2fca6a5828bf286 (patch) | |
tree | fb396118339319406daf7f6782782eaef31b3b53 /fs/proc | |
parent | f4b9a988685da6386d7f9a72df3098bcc3270526 (diff) | |
download | linux-fsl-qoriq-13f0feafa6b8aead57a2a328e2fca6a5828bf286.tar.xz |
mm_for_maps: simplify, use ptrace_may_access()
It would be nice to kill __ptrace_may_access(). It requires task_lock(),
but this lock is only needed to read mm->flags in the middle.
Convert mm_for_maps() to use ptrace_may_access(), this also simplifies
the code a little bit.
Also, we do not need to take ->mmap_sem in advance. In fact I think
mm_for_maps() should not play with ->mmap_sem at all, the caller should
take this lock.
With or without this patch, without ->cred_guard_mutex held we can race
with exec() and get the new ->mm but check old creds.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'fs/proc')
-rw-r--r-- | fs/proc/base.c | 23 |
1 files changed, 11 insertions, 12 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 3ce5ae9..917f338 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -237,20 +237,19 @@ struct mm_struct *mm_for_maps(struct task_struct *task) struct mm_struct *mm = get_task_mm(task); if (!mm) return NULL; + if (mm != current->mm) { + /* + * task->mm can be changed before security check, + * in that case we must notice the change after. + */ + if (!ptrace_may_access(task, PTRACE_MODE_READ) || + mm != task->mm) { + mmput(mm); + return NULL; + } + } down_read(&mm->mmap_sem); - task_lock(task); - if (task->mm != mm) - goto out; - if (task->mm != current->mm && - __ptrace_may_access(task, PTRACE_MODE_READ) < 0) - goto out; - task_unlock(task); return mm; -out: - task_unlock(task); - up_read(&mm->mmap_sem); - mmput(mm); - return NULL; } static int proc_pid_cmdline(struct task_struct *task, char * buffer) |