From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 28F2630F818 for ; Tue, 17 Mar 2026 16:25:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773764706; cv=none; b=Z+i/vnvE/gOv+GWIgNHFvRbQRl72bUVg086qF3Q0I/ih1bxvMfaeU7IyGkzBnRUti5INJD+anqqpAWG6UXDFYP2iRslXSQJj2lnK719ChTTrAfO128A5Z6I+VXdDqREwYP1Zgbwjk/a2IjO6TPPhmc8pEmSmTkW4t4xWjo/OOus= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773764706; c=relaxed/simple; bh=aG9KWY3cqvaH3qRzTt/gRb7ZJCNg1ybMOukZ535BBKk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aP5Kz9doQ55AUuidNDsrWWO0Va5k8rmkC1S0WOluQc74v1qT3uZgJ6y9qjzee2T5g6Y7VbPX36GIedg8WRNpTWUNtpdGGaA6IvAov9k/kBMPxQysibdi0Yg0INTtfQQHRQ6peCJUzQ6P+LxROQZkYz08gyfcLBz5A3U8gwQXcsA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=j7HUBtFx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="j7HUBtFx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 70F49C4CEF7; Tue, 17 Mar 2026 16:25:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773764705; bh=aG9KWY3cqvaH3qRzTt/gRb7ZJCNg1ybMOukZ535BBKk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=j7HUBtFxRrdRMzgmntMegKJi6L/pmE5Gd/qHxZSXrhE19sP7IEm4/nBd1onmbg5bc sB76hVIybrMBZytxKWSu4IlIYbE1T/g5Suimap5mpSYVyVRTSescrY7OMI8hdVvUoi 0L5lAYeHLJ5bDNT+MDhsbikVOLFJFWHjNaBUI1dfZZmmbyEQHUojEGMO6TFVi6XEpr P21CR5O7v/uyepZ5yrppP4dPNZHNfBnRSR3oj8JYbdBkTrtHsM/9Q7WvZ+xk9snral FUCIu/fU6Mr+tRk62IjK8IhWV6XupiBcrYxsxAzyfeqTYS7KD5kVJj13YUnFYe65Nz gEpHYeiCbgePg== From: Sasha Levin To: stable@vger.kernel.org Cc: Alexander Potapenko , Marco Elver , Andrey Konovalov , Andrey Ryabinin , Dmitry Vyukov , Ernesto Martinez Garcia , Greg KH , Kees Cook , Andrew Morton , Sasha Levin Subject: [PATCH 6.1.y] mm/kfence: disable KFENCE upon KASAN HW tags enablement Date: Tue, 17 Mar 2026 12:25:01 -0400 Message-ID: <20260317162502.213232-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <2026031743-sixth-control-6db4@gregkh> References: <2026031743-sixth-control-6db4@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Alexander Potapenko [ Upstream commit 09833d99db36d74456a4d13eb29c32d56ff8f2b6 ] KFENCE does not currently support KASAN hardware tags. As a result, the two features are incompatible when enabled simultaneously. Given that MTE provides deterministic protection and KFENCE is a sampling-based debugging tool, prioritize the stronger hardware protections. Disable KFENCE initialization and free the pre-allocated pool if KASAN hardware tags are detected to ensure the system maintains the security guarantees provided by MTE. Link: https://lkml.kernel.org/r/20260213095410.1862978-1-glider@google.com Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Signed-off-by: Alexander Potapenko Suggested-by: Marco Elver Reviewed-by: Marco Elver Cc: Andrey Konovalov Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Ernesto Martinez Garcia Cc: Greg KH Cc: Kees Cook Cc: Signed-off-by: Andrew Morton [ Context ] Signed-off-by: Sasha Levin --- mm/kfence/core.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/mm/kfence/core.c b/mm/kfence/core.c index edf6deb382b67..5efb063aa5c53 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -844,6 +845,20 @@ void __init kfence_alloc_pool(void) if (!kfence_sample_interval) return; + /* + * If KASAN hardware tags are enabled, disable KFENCE, because it + * does not support MTE yet. + */ + if (kasan_hw_tags_enabled()) { + pr_info("disabled as KASAN HW tags are enabled\n"); + if (__kfence_pool) { + memblock_free(__kfence_pool, KFENCE_POOL_SIZE); + __kfence_pool = NULL; + } + kfence_sample_interval = 0; + return; + } + /* if the pool has already been initialized by arch, skip the below. */ if (__kfence_pool) return; -- 2.51.0