# Re: [PATCH v2] net: ethernet: dec: tulip: de4x5: fix possible array overflows in type3_infoblock()

From: Arnd Bergmann
Date: Thu Nov 18 2021 - 02:06:11 EST

On Thu, Nov 18, 2021 at 8:01 AM Teng Qi <starmiku1207184332@xxxxxxxxx> wrote:
>
> The definition of macro MOTO_SROM_BUG is:
> #define MOTO_SROM_BUG (lp->active == 8 && (get_unaligned_le32(
> dev->dev_addr) & 0x00ffffff) == 0x3e0008)
>
> and the if statement
> if (MOTO_SROM_BUG) lp->active = 0;
>
> using this macro indicates lp->active could be 8. If lp->active is 8 and
> the second comparison of this macro is false. lp->active will remain 8 in:
> lp->phy[lp->active].gep = (*p ? p : NULL); p += (2 * (*p) + 1);
> lp->phy[lp->active].rst = (*p ? p : NULL); p += (2 * (*p) + 1);
> lp->phy[lp->active].mc = get_unaligned_le16(p); p += 2;
> lp->phy[lp->active].ana = get_unaligned_le16(p); p += 2;
> lp->phy[lp->active].fdx = get_unaligned_le16(p); p += 2;
> lp->phy[lp->active].ttm = get_unaligned_le16(p); p += 2;
> lp->phy[lp->active].mci = *p;
>
> However, the length of array lp->phy is 8, so array overflows can occur.
> To fix these possible array overflows, we first check lp->active and then
> return -EINVAL if it is greater or equal to ARRAY_SIZE(lp->phy) (i.e. 8).
>
> Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx>
> Signed-off-by: Teng Qi <starmiku1207184332@xxxxxxxxx>

Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>