On Mon, Jul 12, 2021 at 11:38:43AM -0700, Brian Norris wrote: > On Sun, Jul 11, 2021 at 6:43 PM Pkshih <pkshih@xxxxxxxxxxx> wrote: > > > -----Original Message----- > > > From: Len Baker [mailto:len.baker@xxxxxxx] > > > > > > 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. > > > > > > Fix it using the ARRAY_SIZE macro. > > > > > > Cc: stable@xxxxxxxxxxxxxxx > > > Addresses-Coverity-ID: 1461515 ("Out-of-bounds write") > > Coverity seems to be giving a false warning here. I presume it's > taking the |len| comparison as proof that |len| might be as large as > TRX_BD_IDX_MASK, but as noted below, that's not really true; the |len| > comparison is really just dead code. I agree. > > > Fixes: e3037485c68ec ("rtw88: new Realtek 802.11ac driver") > > > Signed-off-by: Len Baker <len.baker@xxxxxxx> > > > To prevent the 'len' argument from exceeding the array size of rx_ring->buff, I > > suggest to add another checking statement, like > > > > if (len > ARRAY_SIZE(rx_ring->buf)) { > > rtw_err(rtwdev, "len %d exceeds maximum RX ring buffer\n", len); > > return -EINVAL; > > } > > That seems like a better idea, if we really need to patch anything. I think it is reasonable to protect any potencial overflow (for example, if this function is used in the future with a parameter greater than 512). It is better to be defensive in this case :) > > But, I wonder if this a false alarm because 'len' is equal to ARRAY_SIZE(rx_ring->buf) > > for now. > > Or to the point: rtw_pci_init_rx_ring() is only ever called with a > fixed constant -- RTK_MAX_RX_DESC_NUM (i.e., 512) -- so the alleged > overflow cannot happen. > > Brian I will send a v2 for review. Thanks, Len
