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 9B1C91A3BD8; Fri, 23 Aug 2024 14:05:27 +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=1724421927; cv=none; b=icDnnuRgXPyQ7djCT+oXpk337pwtJ5oau564NJ4qmp8p1anIT8tTvm68eohmkPa2zVu7XzWOMrfmc3WHaZ2iYt3OTqYqUCO3oXivdTtdBSufJ8fw5JAkHOqGL21WpXp62d3ENff+Uw8DXkmi2J1UGql5e/yRiuaEaG9NI6YibcE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724421927; c=relaxed/simple; bh=s6a75ygW/XR1hPToCJ4pwziJfz1cgmCxHl4xM3zC+eM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OwypN2IfUtASqn662U5b0qZN10KqTw5HC/L/S/nfBjcMCky48JMIMhXkHxkebbEozzhSIFOh7GDLNoFlSPuX9oVY/3VeXVKnxaPLylRjaFrrZCAdivFdZBQZvC9N6jXanvqLy61/GnxIP1cOCOIzdRI/VSE2zwwnCG40GNI+xz8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ROXeMxbw; 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="ROXeMxbw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2B5BC4AF10; Fri, 23 Aug 2024 14:05:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724421927; bh=s6a75ygW/XR1hPToCJ4pwziJfz1cgmCxHl4xM3zC+eM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ROXeMxbwr+LguoVM9E7coNt+4GOsiRJBQGlaDkbAdP0uPwZTaL1pNsY9IU13RR7GK XjNhnGjqKeuE3rh/D9GYHG1C9EoGxGW792rFF8qh/X+5a0vK2nLJlMxYGI/bbDG78o nucYXP/buSPbS3n+yH/VBG9vO3iy+Sj/fYgez+PuikIhwlL6KPGCeXpYuI1KveWV65 riZ6xqu6x15L63Dq1qYPzh2wXRdfEduoCpTll7AcKkSC+85bNIy4bg3MvTMKxduJLf bK5VfBgk7z4HiP6IzYzZR/DNIaLz8g07XWMAyV0atgLUhvHAbwo5htxfj8MjdADN5m MHdR1r9C5x4ng== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kent Overstreet , Sasha Levin Subject: [PATCH AUTOSEL 5.15 8/9] lib/generic-radix-tree.c: Fix rare race in __genradix_ptr_alloc() Date: Fri, 23 Aug 2024 10:04:55 -0400 Message-ID: <20240823140507.1975524-8-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240823140507.1975524-1-sashal@kernel.org> References: <20240823140507.1975524-1-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 5.15.165 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