diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2009-07-10 03:27:38 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-08-16 14:19:13 -0700 |
| commit | 17dc3e97d6d51df33cb6e35fabb62b91ef14cf2c (patch) | |
| tree | 756968feee8f64e4d44264a3c0adfdd6eeae7cd9 /fs/proc/base.c | |
| parent | 95d7e670e3158b6a52a8279290a0d6f7047250b4 (diff) | |
mm_for_maps: shift down_read(mmap_sem) to the caller
commit 00f89d218523b9bf6b522349c039d5ac80aa536d upstream.
mm_for_maps() takes ->mmap_sem after security checks, this looks
strange and obfuscates the locking rules. Move this lock to its
single caller, m_start().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs/proc/base.c')
| -rw-r--r-- | fs/proc/base.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 34ebebe1eec..8764fffd737 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -235,9 +235,8 @@ static int check_mem_permission(struct task_struct *task) 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) { + + if (mm && mm != current->mm) { /* * task->mm can be changed before security check, * in that case we must notice the change after. @@ -245,10 +244,9 @@ struct mm_struct *mm_for_maps(struct task_struct *task) if (!ptrace_may_access(task, PTRACE_MODE_READ) || mm != task->mm) { mmput(mm); - return NULL; + mm = NULL; } } - down_read(&mm->mmap_sem); return mm; } |