pagemap: close races with suid execve

just use mm_for_maps()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 5 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 60b914860f81..c966413c139b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -729,7 +729,8 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
                 goto out;
 
         ret = -EACCES;
-        if (!ptrace_may_access(task, PTRACE_MODE_READ))
+        mm = mm_for_maps(task);
+        if (!mm)
                 goto out_task;
 
         ret = -EINVAL;
@@ -742,10 +743,6 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
         if (!count)
                 goto out_task;
 
-        mm = get_task_mm(task);
-        if (!mm)
-                goto out_task;
-
         pm.len = PM_ENTRY_BYTES * (PAGEMAP_WALK_SIZE >> PAGE_SHIFT);
         pm.buffer = kmalloc(pm.len, GFP_TEMPORARY);
         ret = -ENOMEM;