From: Stanislaw Gruszka <sgruszka@xxxxxxxxxx> commit 9186a1fd9ed190739423db84bc344d258ef3e3d7 upstream. 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: [<ffffffff8130924d>] strnlen+0xd/0x40 Call Trace: [<ffffffff8130ad2e>] string.isra.3+0x3e/0xd0 [<ffffffff8130bf99>] vsnprintf+0x219/0x640 [<ffffffff8130c481>] vscnprintf+0x11/0x30 [<ffffffff81061585>] vprintk_emit+0x115/0x4f0 [<ffffffff81657bd5>] printk+0x61/0x63 [<ffffffffa048987f>] ieee80211_chswitch_done+0xaf/0xd0 [mac80211] [<ffffffffa04e7b34>] iwl_chswitch_done+0x34/0x40 [iwldvm] [<ffffffffa04f83c3>] iwlagn_commit_rxon+0x2a3/0xdc0 [iwldvm] [<ffffffffa04ebc50>] ? iwlagn_set_rxon_chain+0x180/0x2c0 [iwldvm] [<ffffffffa04e5e76>] iwl_set_mode+0x36/0x40 [iwldvm] [<ffffffffa04e5f0d>] iwlagn_mac_remove_interface+0x8d/0x1b0 [iwldvm] [<ffffffffa0459b3d>] 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 Reported-by: Lukasz Jagiello <jagiello.lukasz@xxxxxxxxx> Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx> Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx> Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> [bwh: Backported to 3.2: adjust context, filename] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> [wujg: Backported to 3.4: - adjust context] Signed-off-by: Jianguo Wu <wujianguo@xxxxxxxxxx> --- drivers/net/wireless/iwlwifi/iwl-core.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/iwl-core.c b/drivers/net/wireless/iwlwifi/iwl-core.c index 46490d3..75ebb82 100644 --- a/drivers/net/wireless/iwlwifi/iwl-core.c +++ b/drivers/net/wireless/iwlwifi/iwl-core.c @@ -801,7 +801,10 @@ 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); } -- 1.7.7 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html