From 9186a1fd9ed190739423db84bc344d258ef3e3d7 Mon Sep 17 00:00:00 2001 From: Stanislaw Gruszka Date: Fri, 26 Jul 2013 15:29:09 +0200 Subject: [PATCH] iwlwifi: dvm: fix calling ieee80211_chswitch_done() with NULL If channel switch is pending and we remove interface we can crash like showed below due to passing NULL vif to mac80211: BUG: unable to handle kernel paging request at fffffffffffff8cc IP: [] strnlen+0xd/0x40 Call Trace: [] string.isra.3+0x3e/0xd0 [] vsnprintf+0x219/0x640 [] vscnprintf+0x11/0x30 [] vprintk_emit+0x115/0x4f0 [] printk+0x61/0x63 [] ieee80211_chswitch_done+0xaf/0xd0 [mac80211] [] iwl_chswitch_done+0x34/0x40 [iwldvm] [] iwlagn_commit_rxon+0x2a3/0xdc0 [iwldvm] [] ? iwlagn_set_rxon_chain+0x180/0x2c0 [iwldvm] [] iwl_set_mode+0x36/0x40 [iwldvm] [] iwlagn_mac_remove_interface+0x8d/0x1b0 [iwldvm] [] ieee80211_do_stop+0x29d/0x7f0 [mac80211] This is because we nulify ctx->vif in iwlagn_mac_remove_interface() before calling some other functions that teardown interface. To fix just check ctx->vif on iwl_chswitch_done(). We should not call ieee80211_chswitch_done() as channel switch works were already canceled by mac80211 in ieee80211_do_stop() -> ieee80211_mgd_stop(). Resolve: https://bugzilla.redhat.com/show_bug.cgi?id=979581 Cc: stable@vger.kernel.org Reported-by: Lukasz Jagiello Signed-off-by: Stanislaw Gruszka Reviewed-by: Emmanuel Grumbach Signed-off-by: Johannes Berg --- drivers/net/wireless/iwlwifi/dvm/mac80211.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/iwlwifi/dvm/mac80211.c b/drivers/net/wireless/iwlwifi/dvm/mac80211.c index 822f1a00efbb..319387263e12 100644 --- a/drivers/net/wireless/iwlwifi/dvm/mac80211.c +++ b/drivers/net/wireless/iwlwifi/dvm/mac80211.c @@ -1068,7 +1068,10 @@ void iwl_chswitch_done(struct iwl_priv *priv, bool is_success) if (test_bit(STATUS_EXIT_PENDING, &priv->status)) return; - if (test_and_clear_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status)) + if (!test_and_clear_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status)) + return; + + if (ctx->vif) ieee80211_chswitch_done(ctx->vif, is_success); } -- 2.20.1