wifi: mac80211: allocate backup ieee80211_nan_sched_cfg off stack

The ieee80211_nan_sched_cfg structure is too large to keep on the
per thread stack:

net/mac80211/nan.c:251:5: error: stack frame size (1560) exceeds limit (1536) in 'ieee80211_nan_set_local_sched' [-Werror,-Wframe-larger-than]
  251 | int ieee80211_nan_set_local_sched(struct ieee80211_sub_if_data *sdata,

Allocate this dynamically using kmalloc_obj() to reduce the stack
usage of this function to a manageable 344 bytes for the same
configuration.

Fixes: 589c06e8fdee ("wifi: mac80211: add NAN local schedule support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260611130100.3387714-1-arnd@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/nan.c b/net/mac80211/nan.c
index 1800bb96dd294fd0df210ad868ab7bfe183b087a..19e08661be43ab06d8ba157d768c4e02fd879331 100644 (file)
--- a/net/mac80211/nan.c
+++ b/net/mac80211/nan.c
@@ -253,9 +253,12 @@ int ieee80211_nan_set_local_sched(struct ieee80211_sub_if_data *sdata,
 {
        struct ieee80211_nan_channel *sched_idx_to_chan[IEEE80211_NAN_MAX_CHANNELS] = {};
        struct ieee80211_nan_sched_cfg *sched_cfg = &sdata->vif.cfg.nan_sched;
-       struct ieee80211_nan_sched_cfg backup_sched;
+       struct ieee80211_nan_sched_cfg *backup_sched __free(kfree) = kmalloc_obj(*backup_sched);
        int ret;
 
+       if (!backup_sched)
+               return -ENOMEM;
+
        if (sched->n_channels > IEEE80211_NAN_MAX_CHANNELS)
                return -EOPNOTSUPP;
 
@@ -275,13 +278,13 @@ int ieee80211_nan_set_local_sched(struct ieee80211_sub_if_data *sdata,
 
        bitmap_zero(sdata->u.nan.removed_channels, IEEE80211_NAN_MAX_CHANNELS);
 
-       memcpy(backup_sched.schedule, sched_cfg->schedule,
-              sizeof(backup_sched.schedule));
-       memcpy(backup_sched.channels, sched_cfg->channels,
-              sizeof(backup_sched.channels));
-       memcpy(backup_sched.avail_blob, sched_cfg->avail_blob,
-              sizeof(backup_sched.avail_blob));
-       backup_sched.avail_blob_len = sched_cfg->avail_blob_len;
+       memcpy(backup_sched->schedule, sched_cfg->schedule,
+              sizeof(backup_sched->schedule));
+       memcpy(backup_sched->channels, sched_cfg->channels,
+              sizeof(backup_sched->channels));
+       memcpy(backup_sched->avail_blob, sched_cfg->avail_blob,
+              sizeof(backup_sched->avail_blob));
+       backup_sched->avail_blob_len = sched_cfg->avail_blob_len;
 
        memcpy(sched_cfg->avail_blob, sched->nan_avail_blob,
               sched->nan_avail_blob_len);
@@ -380,17 +383,17 @@ err:
                if (!chan_def->chan)
                        continue;
 
-               if (!cfg80211_chandef_identical(&backup_sched.channels[i].chanreq.oper,
+               if (!cfg80211_chandef_identical(&backup_sched->channels[i].chanreq.oper,
                                                chan_def))
                        ieee80211_nan_remove_channel(sdata,
                                                     &sched_cfg->channels[i]);
        }
 
        /* Re-add all backed up channels */
-       for (int i = 0; i < ARRAY_SIZE(backup_sched.channels); i++) {
+       for (int i = 0; i < ARRAY_SIZE(backup_sched->channels); i++) {
                struct ieee80211_nan_channel *chan = &sched_cfg->channels[i];
 
-               *chan = backup_sched.channels[i];
+               *chan = backup_sched->channels[i];
 
                /*
                 * For deferred update, no channels were removed and the channel
@@ -421,11 +424,11 @@ err:
                }
        }
 
-       memcpy(sched_cfg->schedule, backup_sched.schedule,
-              sizeof(backup_sched.schedule));
-       memcpy(sched_cfg->avail_blob, backup_sched.avail_blob,
-              sizeof(backup_sched.avail_blob));
-       sched_cfg->avail_blob_len = backup_sched.avail_blob_len;
+       memcpy(sched_cfg->schedule, backup_sched->schedule,
+              sizeof(backup_sched->schedule));
+       memcpy(sched_cfg->avail_blob, backup_sched->avail_blob,
+              sizeof(backup_sched->avail_blob));
+       sched_cfg->avail_blob_len = backup_sched->avail_blob_len;
        sched_cfg->deferred = false;
        bitmap_zero(sdata->u.nan.removed_channels, IEEE80211_NAN_MAX_CHANNELS);