On Fri, Jul 16, 2021 at 8:54 AM Len Baker <len.baker@xxxxxxx> wrote: > > In the rtw_pci_init_rx_ring function the "if (len > TRX_BD_IDX_MASK)" > statement guarantees that len is less than or equal to GENMASK(11, 0) or > in other words that len is less than or equal to 4095. However the > rx_ring->buf has a size of RTK_MAX_RX_DESC_NUM (defined as 512). This > way it is possible an out-of-bounds write in the for statement due to > the i variable can exceed the rx_ring->buff size. > > However, this overflow never happens due to the rtw_pci_init_rx_ring is > only ever called with a fixed constant of RTK_MAX_RX_DESC_NUM. But it is > better to be defensive in this case and add a new check to avoid > overflows if this function is called in a future with a value greater > than 512. > > Cc: stable@xxxxxxxxxxxxxxx This kinda seems excessive, considering we absolutely know this is not currently a bug. But then, LWN nicely highlighted this thread, which reminds me that even without the Cc stable, this is likely to unnecessarily get picked up: https://lwn.net/ml/linux-kernel/YO0zXVX9Bx9QZCTs@xxxxxxxxx/ And I guess silencing Coverity is a desirable goal in many cases, even if Coverity is being a bit trigger-happy. So, *shrug*. > Addresses-Coverity-ID: 1461515 ("Out-of-bounds write") > Fixes: e3037485c68ec ("rtw88: new Realtek 802.11ac driver") > Signed-off-by: Len Baker <len.baker@xxxxxxx> > --- > Changelog v1 -> v2 > - Remove the macro ARRAY_SIZE from the for loop (Pkshih, Brian Norris). > - Add a new check for the len variable (Pkshih, Brian Norris). Reviewed-by: Brian Norris <briannorris@xxxxxxxxxxxx> Thanks.
