1. There is no reason to reset ->tail_vma in m_start(), if we return
IS_ERR_OR_NULL() it won't be used.
2. m_start() also clears priv->task to ensure that m_stop() won't use
the stale pointer if we fail before get_task_struct(). But this is
ugly and confusing, move this initialization in m_stop().
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
fs/proc/task_mmu.c | 9 +++------
1 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index c4c8825..5f7fb45 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -145,17 +145,12 @@ static void *m_start(struct seq_file *m, loff_t *pos)
struct vm_area_struct *vma, *tail_vma = NULL;
loff_t l = *pos;
- /* Clear the per syscall fields in priv */
- priv->task = NULL;
- priv->tail_vma = NULL;
-
/*
* We remember last_addr rather than next_addr to hit with
* vmacache most of the time. We have zero last_addr at
* the beginning and also after lseek. We will have -1 last_addr
* after the end of the vmas.
*/
-
if (last_addr == -1UL)
return NULL;
@@ -227,8 +222,10 @@ static void m_stop(struct seq_file *m, void *v)
if (!IS_ERR_OR_NULL(v))
vma_stop(priv);
- if (priv->task)
+ if (priv->task) {
put_task_struct(priv->task);
+ priv->task = NULL;
+ }
}
static int proc_maps_open(struct inode *inode, struct file *file,
--
1.5.5.1
--
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