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. > > 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. > 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
