On Sun, Jul 12, 2020 at 08:10:12PM +0900, Tetsuo Handa wrote:
> [...]
> @@ -1125,6 +1134,11 @@ int vc_allocate(unsigned int currcons) /* return 0 on
> success */
> if (!*vc->vc_uni_pagedir_loc)
> con_set_default_unimap(vc);
>
> + err = -EINVAL;
> + if (vc->vc_cols > VC_MAXCOL || vc->vc_rows > VC_MAXROW ||
> + vc->vc_screenbuf_size > KMALLOC_MAX_SIZE || !vc->vc_screenbuf_size)
> + goto err_free;
> + err = -ENOMEM;
> vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_KERNEL);
> if (!vc->vc_screenbuf)
> goto err_free;
I realize this patch already landed, but I wanted to remind folks to
use the check_*_overflow() helpers, which can make a lot of this kind
of stuff easier to deal with.
For example, in this case, I think visual_init() could likely be changed
to return success/failure and do all the sanity checking:
if (check_shl_overflow(vc->vc_cols, 1, &vc->vc_size_row) ||
check_mul_overflow(vc->vc_rows, vc->vc_size_row,
&vc->vc_screenbuf_size))
return -EINVAL;
--
Kees Cook
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