On 3/27/2024 11:50 AM, Gustavo A. R. Silva wrote: > Prepare for the coming implementation by GCC and Clang of the > __counted_by attribute. Flexible array members annotated with > __counted_by can have their accesses bounds-checked at run-time > via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE > (for strcpy/memcpy-family functions). > > Also, -Wflex-array-member-not-at-end is coming in GCC-14, and we are > getting ready to enable it globally. > > So, use the `DEFINE_FLEX()` helper for an on-stack definition of > a flexible structure where the size of the flexible-array member > is known at compile-time, and refactor the rest of the code, > accordingly. > > So, with these changes, fix the following warning: > drivers/net/wireless/ath/wil6210/cfg80211.c:896:43: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > Link: https://github.com/KSPP/linux/issues/202 > Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> > --- > drivers/net/wireless/ath/wil6210/cfg80211.c | 22 ++++++++++----------- > drivers/net/wireless/ath/wil6210/wmi.h | 2 +- > 2 files changed, 11 insertions(+), 13 deletions(-) > > diff --git a/drivers/net/wireless/ath/wil6210/cfg80211.c b/drivers/net/wireless/ath/wil6210/cfg80211.c > index dbe4b3478f03..836b49954171 100644 > --- a/drivers/net/wireless/ath/wil6210/cfg80211.c > +++ b/drivers/net/wireless/ath/wil6210/cfg80211.c > @@ -892,10 +892,8 @@ static int wil_cfg80211_scan(struct wiphy *wiphy, > struct wil6210_priv *wil = wiphy_to_wil(wiphy); > struct wireless_dev *wdev = request->wdev; > struct wil6210_vif *vif = wdev_to_vif(wil, wdev); > - struct { > - struct wmi_start_scan_cmd cmd; > - u16 chnl[4]; > - } __packed cmd; > + DEFINE_FLEX(struct wmi_start_scan_cmd, cmd, > + channel_list, num_channels, 4); > uint i, n; > int rc; > > @@ -977,9 +975,9 @@ static int wil_cfg80211_scan(struct wiphy *wiphy, > vif->scan_request = request; > mod_timer(&vif->scan_timer, jiffies + WIL6210_SCAN_TO); > > - memset(&cmd, 0, sizeof(cmd)); > - cmd.cmd.scan_type = WMI_ACTIVE_SCAN; > - cmd.cmd.num_channels = 0; > + memset(cmd, 0, sizeof(*cmd)); Isn't this unnecessary since DEFINE_FLEX() logic "{ .obj.COUNTER = COUNT, }" should result in everything else being zeroed? And if that isn't sufficient, DEFINE_FLEX() itself says we should "Use __struct_size(@NAME) to get compile-time size of it afterwards" Note the current memset won't zero the flex array and hence if the actual number of channels is less than 4 then kernel stack contents could be exposed to firmware. > + cmd->scan_type = WMI_ACTIVE_SCAN; > + cmd->num_channels = 0; > n = min(request->n_channels, 4U); > for (i = 0; i < n; i++) { > int ch = request->channels[i]->hw_value; > @@ -991,7 +989,8 @@ static int wil_cfg80211_scan(struct wiphy *wiphy, > continue; > } > /* 0-based channel indexes */ > - cmd.cmd.channel_list[cmd.cmd.num_channels++].channel = ch - 1; > + cmd->num_channels++; > + cmd->channel_list[cmd->num_channels - 1].channel = ch - 1; > wil_dbg_misc(wil, "Scan for ch %d : %d MHz\n", ch, > request->channels[i]->center_freq); > } > @@ -1007,16 +1006,15 @@ static int wil_cfg80211_scan(struct wiphy *wiphy, > if (rc) > goto out_restore; > > - if (wil->discovery_mode && cmd.cmd.scan_type == WMI_ACTIVE_SCAN) { > - cmd.cmd.discovery_mode = 1; > + if (wil->discovery_mode && cmd->scan_type == WMI_ACTIVE_SCAN) { > + cmd->discovery_mode = 1; > wil_dbg_misc(wil, "active scan with discovery_mode=1\n"); > } > > if (vif->mid == 0) > wil->radio_wdev = wdev; > rc = wmi_send(wil, WMI_START_SCAN_CMDID, vif->mid, > - &cmd, sizeof(cmd.cmd) + > - cmd.cmd.num_channels * sizeof(cmd.cmd.channel_list[0])); > + cmd, struct_size(cmd, channel_list, cmd->num_channels)); > > out_restore: > if (rc) { > diff --git a/drivers/net/wireless/ath/wil6210/wmi.h b/drivers/net/wireless/ath/wil6210/wmi.h > index 71bf2ae27a98..b47606d9068c 100644 > --- a/drivers/net/wireless/ath/wil6210/wmi.h > +++ b/drivers/net/wireless/ath/wil6210/wmi.h > @@ -474,7 +474,7 @@ struct wmi_start_scan_cmd { > struct { > u8 channel; > u8 reserved; > - } channel_list[]; > + } channel_list[] __counted_by(num_channels); > } __packed; > > #define WMI_MAX_PNO_SSID_NUM (16)
