From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CABA133D6FD; Wed, 30 Sep 2026 16:30:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790785843; cv=none; b=cfHXsnEAiV5yvgV/NJGHXYnaCSbr2c2QLhO51Cu+PoR+7KvpqIols4Ow/oEHr8ZbyWS6B7TeThizq0nGPaG7LiIZBBtw+ZFTlmvWkzO3vHNEpEw9VOdXA5iZWy3s+5JCaHRPaG1Y0MqeE3JKRRIoofTmlUAMUL6lI+OPpJzzMPU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790785843; c=relaxed/simple; bh=nsZ26m1U04ORIA97y0aeQ3oP+BOv7waXtkh+yjMka2Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gvCQlheB2t5skvFy/vzyZ7P0fnEr6yyMYj8bQw684ZzAdsWEh+kq3M/iFWMfP8z/0WOThxYJEn1IxEx0uaB/99AzbBe4gSVvrSFCfCjmEpNTmlwcsvk4Btdr48ODcCoSZJJjYqrz6Fj1NBTlOtXtyBjpnw0mFCWYX3nSeZC1dl0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hujeU8k5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="hujeU8k5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3101C1F000FF; Wed, 30 Sep 2026 16:30:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790785841; bh=0B7kWZ7DaoKH9C0lTq5UlLnNUY58kheA2a/ojoPg/vU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=hujeU8k5x/LJm+AE+el6MVlKdGaZ+Oy4mjDYmF7/9fG+ZhMclF+i+0l8Buk4cbvIX h/tYxNLro9Jiwjl4z74rPW6CKGxnAbQzwbIDVxKr62tZRgxTwRdPCl8p2BQLpxMsJ4 tuz30b3Ro31vw6S1R4LyaBqVL6Pr6fySGPF9vNuA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Karl Mehltretter , Jarkko Sakkinen , Sasha Levin Subject: [PATCH 6.1 652/982] keys: fix lost wakeup when reaping a dead key type Date: Wed, 30 Sep 2026 17:23:08 +0200 Message-ID: <20260930152430.770536794@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152416.775402466@linuxfoundation.org> References: <20260930152416.775402466@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Karl Mehltretter [ Upstream commit 2725ab3f5ad1c5f375c7c9fee4af02a9b138f701 ] clear_bit() is atomic with respect to the word it modifies, but it is an unordered operation: it implies no memory barrier on either side (Documentation/atomic_bitops.txt). key_garbage_collector() clears KEY_GC_REAPING_KEYTYPE with clear_bit() and calls wake_up_bit() after reaping a dead key type. wake_up_bit() uses a lockless waitqueue check and requires a full barrier after the clear. The existing smp_mb() is before clear_bit(), so nothing orders the clear against that check. The GC can see an empty waitqueue while unregister_key_type() still sees the bit set. The final wakeup is then lost, leaving module unload stuck in wait_on_bit(). Use clear_and_wake_up_bit(). Its clear_bit_unlock() has RELEASE semantics, so the completed GC work stays ordered before the clear, and its smp_mb__after_atomic() orders the clear before the waitqueue check. Fixes: 0c061b5707ab ("KEYS: Correctly destroy key payloads when their keytype is removed") Assisted-by: Claude:claude-fable-5 Signed-off-by: Karl Mehltretter Link: https://lore.kernel.org/r/20260821025327.61488-1-kmehltretter@gmail.com Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen Signed-off-by: Sasha Levin --- security/keys/gc.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/security/keys/gc.c b/security/keys/gc.c index eaddaceda14ea..285ebbf490f04 100644 --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -324,9 +324,7 @@ static void key_garbage_collector(struct work_struct *work) if (unlikely(gc_state & KEY_GC_REAPING_DEAD_3)) { kdebug("dead wake"); - smp_mb(); - clear_bit(KEY_GC_REAPING_KEYTYPE, &key_gc_flags); - wake_up_bit(&key_gc_flags, KEY_GC_REAPING_KEYTYPE); + clear_and_wake_up_bit(KEY_GC_REAPING_KEYTYPE, &key_gc_flags); } if (gc_state & KEY_GC_REAP_AGAIN) -- 2.53.0