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 14:27:35 -0700 |
| commit | 60634e4b830850bb38016f1e6a7a7358eba8118c (patch) | |
| tree | 48762263e12695b03519922263c80625c7c60cf8 | |
| parent | a79c30e57c0eac03aae8be4649958f8592141d20 (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>
| -rw-r--r-- | fs/proc/base.c | 8 | ||||
| -rw-r--r-- | fs/proc/task_mmu.c | 1 | ||||
| -rw-r--r-- | fs/proc/task_nommu.c | 1 |
3 files changed, 5 insertions, 5 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 500b7af91b5c..76f9ffc6bdde 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -240,9 +240,8 @@ 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. @@ -250,10 +249,9 @@ 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; } diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index c7f64a9f11b1..d8be92a171f3 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -119,6 +119,7 @@ static void *m_start(struct seq_file *m, loff_t *pos) mm = mm_for_maps(priv->task); if (!mm) return NULL; + down_read(&mm->mmap_sem); tail_vma = get_gate_vma(priv->task); priv->tail_vma = tail_vma; diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c index 5d84e7121df8..737d219c7993 100644 --- a/fs/proc/task_nommu.c +++ b/fs/proc/task_nommu.c @@ -137,6 +137,7 @@ static void *m_start(struct seq_file *m, loff_t *pos) priv->task = NULL; return NULL; } + down_read(&mm->mmap_sem); /* start from the Nth VMA */ for (vml = mm->context.vmlist; vml; vml = vml->next) |