Hi all! On 4/7/21 14:02, Kees Cook wrote: > On Wed, Mar 31, 2021 at 04:45:34PM -0500, Gustavo A. R. Silva wrote: >> Fix the following out-of-bounds warning by enclosing >> some structure members into new struct req: >> >> arch/x86/include/asm/string_32.h:182:25: warning: '__builtin_memcpy' offset [39, 108] from the object at 'sig' is out of the bounds of referenced subobject 'beacon_period' with type 'short unsigned int' at offset 36 [-Warray-bounds] >> >> Refactor the code, accordingly: >> >> $ pahole -C wl3501_join_req drivers/net/wireless/wl3501_cs.o >> struct wl3501_join_req { >> u16 next_blk; /* 0 2 */ >> u8 sig_id; /* 2 1 */ >> u8 reserved; /* 3 1 */ >> struct iw_mgmt_data_rset operational_rset; /* 4 10 */ >> u16 reserved2; /* 14 2 */ >> u16 timeout; /* 16 2 */ >> u16 probe_delay; /* 18 2 */ >> u8 timestamp[8]; /* 20 8 */ >> u8 local_time[8]; /* 28 8 */ >> struct { >> u16 beacon_period; /* 36 2 */ >> u16 dtim_period; /* 38 2 */ >> u16 cap_info; /* 40 2 */ >> u8 bss_type; /* 42 1 */ >> u8 bssid[6]; /* 43 6 */ >> struct iw_mgmt_essid_pset ssid; /* 49 34 */ >> /* --- cacheline 1 boundary (64 bytes) was 19 bytes ago --- */ >> struct iw_mgmt_ds_pset ds_pset; /* 83 3 */ >> struct iw_mgmt_cf_pset cf_pset; /* 86 8 */ >> struct iw_mgmt_ibss_pset ibss_pset; /* 94 4 */ >> struct iw_mgmt_data_rset bss_basic_rset; /* 98 10 */ >> } req; /* 36 72 */ > > This section is the same as a large portion of struct wl3501_scan_confirm: > > struct wl3501_scan_confirm { > u16 next_blk; > u8 sig_id; > u8 reserved; > u16 status; > char timestamp[8]; > char localtime[8]; > > from here > u16 beacon_period; > u16 dtim_period; > u16 cap_info; > u8 bss_type; > u8 bssid[ETH_ALEN]; > struct iw_mgmt_essid_pset ssid; > struct iw_mgmt_ds_pset ds_pset; > struct iw_mgmt_cf_pset cf_pset; > struct iw_mgmt_ibss_pset ibss_pset; > struct iw_mgmt_data_rset bss_basic_rset; > through here > > u8 rssi; > }; > > It seems like maybe extracting that and using it in both structures > would make more sense? If I do this, I would therefore have to make a bunch of other changes, accordingly. I'm OK with that but I'd like to have the opinion of the maintainers on all this. So, I will go and ping them from the cover letter of this series with the hope that we can get some feedback from them. :) They have been silent for a couple of weeks now. > >> >> /* size: 108, cachelines: 2, members: 10 */ >> /* last cacheline: 44 bytes */ >> }; >> >> The problem is that the original code is trying to copy data into a >> bunch of struct members adjacent to each other in a single call to >> memcpy(). Now that a new struct _req_ enclosing all those adjacent >> members is introduced, memcpy() doesn't overrun the length of >> &sig.beacon_period, because the address of the new struct object >> _req_ is used as the destination, instead. >> >> Also, this helps with the ongoing efforts to enable -Warray-bounds and >> avoid confusing the compiler. >> >> Link: https://github.com/KSPP/linux/issues/109 >> Reported-by: kernel test robot <lkp@xxxxxxxxx> >> Build-tested-by: kernel test robot <lkp@xxxxxxxxx> >> Link: https://lore.kernel.org/lkml/60641d9b.2eNLedOGSdcSoAV2%25lkp@xxxxxxxxx/ >> Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> >> --- >> Changes in v2: >> - None. >> >> drivers/net/wireless/wl3501.h | 22 ++++++++++++---------- >> drivers/net/wireless/wl3501_cs.c | 4 ++-- >> 2 files changed, 14 insertions(+), 12 deletions(-) >> >> diff --git a/drivers/net/wireless/wl3501.h b/drivers/net/wireless/wl3501.h >> index ef9d605d8c88..774d8cac046d 100644 >> --- a/drivers/net/wireless/wl3501.h >> +++ b/drivers/net/wireless/wl3501.h >> @@ -389,16 +389,18 @@ struct wl3501_join_req { >> u16 probe_delay; >> u8 timestamp[8]; >> u8 local_time[8]; >> - u16 beacon_period; >> - u16 dtim_period; >> - u16 cap_info; >> - u8 bss_type; >> - u8 bssid[ETH_ALEN]; >> - struct iw_mgmt_essid_pset ssid; >> - struct iw_mgmt_ds_pset ds_pset; >> - struct iw_mgmt_cf_pset cf_pset; >> - struct iw_mgmt_ibss_pset ibss_pset; >> - struct iw_mgmt_data_rset bss_basic_rset; >> + struct { >> + u16 beacon_period; >> + u16 dtim_period; >> + u16 cap_info; >> + u8 bss_type; >> + u8 bssid[ETH_ALEN]; >> + struct iw_mgmt_essid_pset ssid; >> + struct iw_mgmt_ds_pset ds_pset; >> + struct iw_mgmt_cf_pset cf_pset; >> + struct iw_mgmt_ibss_pset ibss_pset; >> + struct iw_mgmt_data_rset bss_basic_rset; >> + } req; >> }; >> >> struct wl3501_join_confirm { >> diff --git a/drivers/net/wireless/wl3501_cs.c b/drivers/net/wireless/wl3501_cs.c >> index e149ef81d6cc..399d3bd2ae76 100644 >> --- a/drivers/net/wireless/wl3501_cs.c >> +++ b/drivers/net/wireless/wl3501_cs.c >> @@ -590,7 +590,7 @@ static int wl3501_mgmt_join(struct wl3501_card *this, u16 stas) >> struct wl3501_join_req sig = { >> .sig_id = WL3501_SIG_JOIN_REQ, >> .timeout = 10, >> - .ds_pset = { >> + .req.ds_pset = { >> .el = { >> .id = IW_MGMT_INFO_ELEMENT_DS_PARAMETER_SET, >> .len = 1, >> @@ -599,7 +599,7 @@ static int wl3501_mgmt_join(struct wl3501_card *this, u16 stas) >> }, >> }; >> >> - memcpy(&sig.beacon_period, &this->bss_set[stas].beacon_period, 72); >> + memcpy(&sig.req, &this->bss_set[stas].beacon_period, sizeof(sig.req)); > > If not, then probably something like this should be added to make sure > nothing unexpected happens to change structure sizes: > > BUILD_BUG_ON(sizeof(sig.req) != 72); Yep, this is sensible. Thanks for the feedback! -- Gustavo > >> return wl3501_esbq_exec(this, &sig, sizeof(sig)); >> } >> >> -- >> 2.27.0 >> >