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 D6535205E37; Sat, 12 Oct 2024 11:30:03 +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=1728732603; cv=none; b=fnjFSTHVJ0Hripvc0Pp+b3vPra1eubCy1V3lPFb1dIM8WxuBCu+m8FhsFdGyTPdJWmku8TsDTtTvFSM+PI09qCZQuHvjSi3rbaFWFlC0Oz+hlRjAOYNwtczjOIsXF9r/reBnZZwf7CJrpEmFWu4kJvSYvBlRMDZ9cum8lagK4fc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728732603; c=relaxed/simple; bh=s6a75ygW/XR1hPToCJ4pwziJfz1cgmCxHl4xM3zC+eM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Y7BJWMnjDVuioPgWVUJqQ0pz+7dUTCQExuZxLFTg2dONvhJQ7jMROSgoPCK35UOCFR+BeivlG0/e516MYEqGj57juz6VzlyT6g1vBAytkE/C/gobKh322lSdOh+0Rg+zefRdr31/fcI25L4ma83Fpid19VplXkTI/zEoM2r0Kts= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uvv80uLL; 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="uvv80uLL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D0840C4CED0; Sat, 12 Oct 2024 11:30:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728732603; bh=s6a75ygW/XR1hPToCJ4pwziJfz1cgmCxHl4xM3zC+eM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uvv80uLLEmi5k/bVnS4zRGzdHGFVyj388Al2emQGxAykf8s5ezfBtfv+gbvaC+cIL CVjj994Nlssc6MB+i1PbgXDw8tDWr0DOX1h31nNdx9GeT7jE7Ero+7nDChV1GJkk1A B6Q0SJ5h7LFBTaDWNK+yi9ua9SIGWZ9ao1AeWFpvbggc7FHplPnWXjnFAhoZyQey9Q 2iBF2BVJ9es2EzuIqZVEvAMGMoHyvQ0e1XsWZa2GzK9NyE5B0GwFTRu4jfoYT2w7zH Rz27DkHK8IZTvubMTwVxALSB5u92T0i9LIbTiP/VgDnm7OZFjhtQNr0JOoSe34sdbI xxh+ApTxrxayQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kent Overstreet , Sasha Levin Subject: [PATCH AUTOSEL 5.4 7/7] lib/generic-radix-tree.c: Fix rare race in __genradix_ptr_alloc() Date: Sat, 12 Oct 2024 07:29:42 -0400 Message-ID: <20241012112948.1764454-7-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241012112948.1764454-1-sashal@kernel.org> References: <20241012112948.1764454-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.284 Content-Transfer-Encoding: 8bit From: Kent Overstreet [ Upstream commit b2f11c6f3e1fc60742673b8675c95b78447f3dae ] If we need to increase the tree depth, allocate a new node, and then race with another thread that increased the tree depth before us, we'll still have a preallocated node that might be used later. If we then use that node for a new non-root node, it'll still have a pointer to the old root instead of being zeroed - fix this by zeroing it in the cmpxchg failure path. Signed-off-by: Kent Overstreet Signed-off-by: Sasha Levin --- lib/generic-radix-tree.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/generic-radix-tree.c b/lib/generic-radix-tree.c index f25eb111c0516..34d3ac52de894 100644 --- a/lib/generic-radix-tree.c +++ b/lib/generic-radix-tree.c @@ -131,6 +131,8 @@ void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset, if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) { v = new_root; new_node = NULL; + } else { + new_node->children[0] = NULL; } } -- 2.43.0