On Mon, Oct 09, 2023 at 10:55:32AM -0400, Jason Andryuk wrote:
> This is the function that creates struct p54_cal_database:
>
> static struct p54_cal_database *p54_convert_db(struct pda_custom_wrapper *src,
> size_t total_len)
> {
> struct p54_cal_database *dst;
> size_t payload_len, entries, entry_size, offset;
>
> payload_len = le16_to_cpu(src->len);
> entries = le16_to_cpu(src->entries);
> entry_size = le16_to_cpu(src->entry_size);
> offset = le16_to_cpu(src->offset);
> if (((entries * entry_size + offset) != payload_len) ||
> (payload_len + sizeof(*src) != total_len))
> return NULL;
>
> dst = kmalloc(sizeof(*dst) + payload_len, GFP_KERNEL);
> if (!dst)
> return NULL;
>
> dst->entries = entries;
> dst->entry_size = entry_size;
> dst->offset = offset;
> dst->len = payload_len;
>
> memcpy(dst->data, src->data, payload_len);
> return dst;
> }
>
> You can see that kmalloc is performed with `sizeof(*dst) +
> payload_len`, and payload_len is assigned to ->len.
>
> I don't read Coccinelle, but, if this patch was auto-generated, I
> wonder if the script has an error.
It seems that my Coccinelle script got confused by this:
p54_convert_output_limits():
priv->output_limit = kmalloc(data[1] *
sizeof(struct pda_channel_output_limit) +
sizeof(*priv->output_limit), GFP_KERNEL);
...
priv->output_limit->entry_size =
sizeof(struct pda_channel_output_limit);
priv->output_limit->len = priv->output_limit->entry_size *
priv->output_limit->entries +
priv->output_limit->offset;
It thought "sizeof(struct pda_channel_output_limit)" was the element
count, since it wasn't able to identify the array member here.
Regardless, I've sent a v2 now. :)
--
Kees Cook
