From: Arnd Bergmann Date: Tue, 26 Jan 2016 22:05:31 +0000 (+0100) Subject: mac80211: avoid excessive stack usage in sta_info X-Git-Tag: v3.2.80~104 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=eefa363eb2e49f371f6fc2cd4f4def4de5943fc1;hp=dccef52958cc5d654a8e8be3e1578a2b435c538f mac80211: avoid excessive stack usage in sta_info commit 0ef049dc1167fe834d0ad5d63f89eddc5c70f6e4 upstream. When CONFIG_OPTIMIZE_INLINING is set, the sta_info_insert_finish function consumes more stack than normally, exceeding the 1024 byte limit on ARM: net/mac80211/sta_info.c: In function 'sta_info_insert_finish': net/mac80211/sta_info.c:561:1: error: the frame size of 1080 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] It turns out that there are two functions that put a 'struct station_info' on the stack: __sta_info_destroy_part2 and sta_info_insert_finish, and this structure alone requires up to 792 bytes. Hoping that both are called rarely enough, this replaces the on-stack structure with a dynamic allocation, which unfortunately requires some suboptimal error handling for out-of-memory. The __sta_info_destroy_part2 function is actually affected by the stack usage twice because it calls cfg80211_del_sta_sinfo(), which has another instance of struct station_info on its stack. Signed-off-by: Arnd Bergmann Fixes: 98b6218388e3 ("mac80211/cfg80211: add station events") Fixes: 6f7a8d26e266 ("mac80211: send statistics with delete station event") Signed-off-by: Johannes Berg [bwh: Backported to 3.2: - There's only one instance to fix - Adjust context,indentation - Use 'return' instead of 'goto out_err'] Signed-off-by: Ben Hutchings --- diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c index 1914f5a6d6e7..6dcb080246a0 100644 --- a/net/mac80211/sta_info.c +++ b/net/mac80211/sta_info.c @@ -344,12 +344,16 @@ static int sta_info_finish_insert(struct sta_info *sta, { struct ieee80211_local *local = sta->local; struct ieee80211_sub_if_data *sdata = sta->sdata; - struct station_info sinfo; + struct station_info *sinfo; unsigned long flags; int err = 0; lockdep_assert_held(&local->sta_mtx); + sinfo = kzalloc(sizeof(struct station_info), GFP_KERNEL); + if (!sinfo) + return -ENOMEM; + if (!sta->dummy || dummy_reinsert) { /* notify driver */ if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) @@ -397,12 +401,11 @@ static int sta_info_finish_insert(struct sta_info *sta, ieee80211_sta_debugfs_add(sta); rate_control_add_sta_debugfs(sta); - memset(&sinfo, 0, sizeof(sinfo)); - sinfo.filled = 0; - sinfo.generation = local->sta_generation; - cfg80211_new_sta(sdata->dev, sta->sta.addr, &sinfo, GFP_KERNEL); + sinfo->generation = local->sta_generation; + cfg80211_new_sta(sdata->dev, sta->sta.addr, sinfo, GFP_KERNEL); } + kfree(sinfo); return 0; }