proc: disable mem_write after exec
This change makes mem_write() observe the same constraints as mem_read(). This is particularly important for mem_write as an accidental leak of the fd across an exec could result in arbitrary modification of the target process' memory. IOW, /proc/pid/mem is implicitly close-on-exec. Signed-off-by: Stephen Wilson <wilsons@start.ca> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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@ -850,6 +850,10 @@ static ssize_t mem_write(struct file * file, const char __user *buf,
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if (check_mem_permission(task))
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goto out;
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copied = -EIO;
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if (file->private_data != (void *)((long)current->self_exec_id))
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goto out;
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copied = -ENOMEM;
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page = (char *)__get_free_page(GFP_TEMPORARY);
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if (!page)
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