On Tue, Sep 17, 2024 at 06:08:41PM +0300, Alper Nebi Yasak wrote: > Replace one-element array with a flexible-array member in `struct > mwifiex_ie_types_wildcard_ssid_params` to fix the following warning > on a MT8173 Chromebook (mt8173-elm-hana): > > [ 356.775250] ------------[ cut here ]------------ > [ 356.784543] memcpy: detected field-spanning write (size 6) of single field "wildcard_ssid_tlv->ssid" at drivers/net/wireless/marvell/mwifiex/scan.c:904 (size 1) > [ 356.813403] WARNING: CPU: 3 PID: 742 at drivers/net/wireless/marvell/mwifiex/scan.c:904 mwifiex_scan_networks+0x4fc/0xf28 [mwifiex] > > The "(size 6)" above is exactly the length of the SSID of the network > this device was connected to. The source of the warning looks like: > > ssid_len = user_scan_in->ssid_list[i].ssid_len; > [...] > memcpy(wildcard_ssid_tlv->ssid, > user_scan_in->ssid_list[i].ssid, ssid_len); > > Also adjust a #define that uses sizeof() on this struct to keep the > value same as before. > > Signed-off-by: Alper Nebi Yasak <alpernebiyasak@xxxxxxxxx> > --- > I found these relevant patches that modify other such arrays, where the > second one removes a -1 from some sizeof() calculation: > > https://lore.kernel.org/lkml/Y9xkECG3uTZ6T1dN@work/T/#u > https://lore.kernel.org/lkml/ZsZa5xRcsLq9D+RX@elsanto/T/#u > > So I think we need the +1 to keep things same. But it appears to work > fine without it, so I'm not sure. Maybe it should've had a -1 before > that I would remove with this? Thanks for the investigation and patch! I believe I agree with the other comments, that then "+ 1" isn't necessary. It's just a wasteful extra byte of allocation. Can you send a v2? (Bonus: with the suggested Fixes tag. Double bonus if you test KASAN with __counted_by, for a second patch.) Thanks, Brian
