On Sat 20-08-16 01:00:17, Joe Perches wrote:
[...]
> static int proc_maps_open(struct inode *inode, struct file *file,
> const struct seq_operations *ops, int psize)
> {
> - struct proc_maps_private *priv = __seq_open_private(file, ops, psize);
> + struct proc_maps_private *priv;
> + struct mm_struct *mm;
> +
> + mm = proc_mem_open(inode, PTRACE_MODE_READ);
> + if (IS_ERR(mm))
> + return PTR_ERR(mm);
>
> + priv = __seq_open_private_bufsize(file, ops, psize,
> + mm && mm->map_count ?
> + mm->map_count * 0x300 : PAGE_SIZE);
NAK to this! Seriously, this just gives any random user access to user
defined amount of memory which not accounted, not reclaimable and a
potential consumer of any higher order blocks.
Besides that, at least one show_smap output will always fit inside the
single page and AFAIR (it's been quite a while since I've looked into
seq_file internals) the buffer grows only when the single show doesn't
fit in.
> if (!priv)
> return -ENOMEM;
>
> priv->inode = inode;
> - priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
> - if (IS_ERR(priv->mm)) {
> - int err = PTR_ERR(priv->mm);
> -
> - seq_release_private(inode, file);
> - return err;
> - }
> + priv->mm = mm;
>
> return 0;
> }
> @@ -721,6 +723,25 @@ void __weak arch_show_smap(struct seq_file *m, struct vm_area_struct *vma)
> {
> }
>
> +static void show_val_kb(struct seq_file *m, const char *s, unsigned long num)
> +{
> + char v[32];
> + static const char blanks[7] = {' ', ' ', ' ', ' ',' ', ' ', ' '};
> + int len;
> +
> + len = num_to_str(v, sizeof(v), num >> 10);
> +
> + seq_write(m, s, 16);
> +
> + if (len > 0) {
> + if (len < 8)
> + seq_write(m, blanks, 8 - len);
> +
> + seq_write(m, v, len);
> + }
> + seq_write(m, " kB\n", 4);
> +}
> +
I really do not understand why you insist on code duplication rather
than reuse but if you really insist then just make this (without the
above __seq_open_private_bufsize, re-measure and add the results to the
changelog and repost.
--
Michal Hocko
SUSE Labs
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