The patch titled
Subject: fs/proc/task_mmu.c: don't use task->mm in m_start() and show_*map()
has been added to the -mm tree. Its filename is
fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map.patch
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: fs/proc/task_mmu.c: don't use task->mm in m_start() and show_*map()
get_gate_vma(priv->task->mm) looks ugly and wrong, task->mm can be NULL or
it can changed by exec right after mm_access().
And in theory this race is not harmless, the task can exec and then later
exit and free the new mm_struct. In this case get_task_mm(oldmm) can't
help, get_gate_vma(task->mm) can read the freed/unmapped memory.
I think that priv->task should simply die and hold_task_mempolicy() logic
can be simplified. tail_vma logic asks for cleanups too.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff -puN fs/proc/task_mmu.c~fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map
+++ a/fs/proc/task_mmu.c
@@ -170,7 +170,7 @@ static void *m_start(struct seq_file *m,
return mm;
down_read(&mm->mmap_sem);
- tail_vma = get_gate_vma(priv->task->mm);
+ tail_vma = get_gate_vma(mm);
priv->tail_vma = tail_vma;
hold_task_mempolicy(priv);
/* Start with last addr hint */
@@ -351,12 +351,11 @@ static int show_map(struct seq_file *m,
{
struct vm_area_struct *vma = v;
struct proc_maps_private *priv = m->private;
- struct task_struct *task = priv->task;
show_map_vma(m, vma, is_pid);
if (m->count < m->size) /* vma is copied successfully */
- m->version = (vma != get_gate_vma(task->mm))
+ m->version = (vma != priv->tail_vma)
? vma->vm_start : 0;
return 0;
}
@@ -584,7 +583,6 @@ static void show_smap_vma_flags(struct s
static int show_smap(struct seq_file *m, void *v, int is_pid)
{
struct proc_maps_private *priv = m->private;
- struct task_struct *task = priv->task;
struct vm_area_struct *vma = v;
struct mem_size_stats mss;
struct mm_walk smaps_walk = {
@@ -639,7 +637,7 @@ static int show_smap(struct seq_file *m,
show_smap_vma_flags(m, vma);
if (m->count < m->size) /* vma is copied successfully */
- m->version = (vma != get_gate_vma(task->mm))
+ m->version = (vma != priv->tail_vma)
? vma->vm_start : 0;
return 0;
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
earlyprintk-re-enable-earlyprintk-calling-early_param.patch
fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map.patch
fs-proc-task_mmuc-unify-simplify-do_maps_open-and-numa_maps_open.patch
proc-introduce-proc_mem_open.patch
fs-proc-task_mmuc-shift-mm_access-from-m_start-to-proc_maps_open.patch
fs-proc-task_mmuc-simplify-the-vma_stop-logic.patch
fs-proc-task_mmuc-cleanup-the-tail_vma-horror-in-m_next.patch
fs-proc-task_mmuc-shift-priv-task-=-null-from-m_start-to-m_stop.patch
fs-proc-task_mmuc-kill-the-suboptimal-and-confusing-m-version-logic.patch
fs-proc-task_mmuc-simplify-m_start-to-make-it-readable.patch
fs-proc-task_mmuc-introduce-m_next_vma-helper.patch
fs-proc-task_mmuc-reintroduce-m-version-logic.patch
fs-proc-task_mmuc-update-m-version-in-the-main-loop-in-m_start.patch
fs-proc-task_nommuc-change-maps_open-to-use-__seq_open_private.patch
fs-proc-task_nommuc-shift-mm_access-from-m_start-to-proc_maps_open.patch
fs-proc-task_nommuc-dont-use-priv-task-mm.patch
linux-next.patch
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