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| author | Oleg Nesterov <oleg@redhat.com> | 2009-07-10 03:27:38 +0200 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2009-08-10 20:48:32 +1000 |
| commit | 00f89d218523b9bf6b522349c039d5ac80aa536d (patch) | |
| tree | cde7a8bde2798e4fb3ae28756f6cedd4db9191cc | |
| parent | 13f0feafa6b8aead57a2a328e2fca6a5828bf286 (diff) | |
| download | linux-stable-00f89d218523b9bf6b522349c039d5ac80aa536d.tar.gz linux-stable-00f89d218523b9bf6b522349c039d5ac80aa536d.tar.bz2 linux-stable-00f89d218523b9bf6b522349c039d5ac80aa536d.zip | |
mm_for_maps: shift down_read(mmap_sem) to the caller
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>
| -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 917f338a6739..f3c2e4085fed 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; } diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 6f61b7cc32e0..9bd8be1d235c 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 64a72e2e7650..8f5c05d3dbd3 100644 --- a/fs/proc/task_nommu.c +++ b/fs/proc/task_nommu.c @@ -189,6 +189,7 @@ 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 (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) |