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 4705E192581; Tue, 10 Sep 2024 10:04:53 +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=1725962693; cv=none; b=e9HUp02w5iA1Q8DaEvX/vsu3gK8Bt2eRp35xktifboVB3DNKolvritLCdnXj3Bh72J5qw0l9UvqkeIUPMEutlWWXjdcxEek0Ws33tm3ZzGoOlebfI4Ug4KbHT5+F2X2MFywqJ18REWvize1NaY9FLpyoOI+yUhTYwvEASR6h8QY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725962693; c=relaxed/simple; bh=196ycIMGKaN3v8nAAksoHcYeau6Mzn7Gx1SaW4EphN0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JklGwyPG5PDmPHvLhM9B6nppm0//QLGOxUy+qBGAaOiX7eoBFGiIFAGAHMGziCows9sQWF/LRBaEwKyZhTeI9ZHXBxZCcc0Zys8VvqrMWSZH+Ae+CqVOLT++a9Z5z+DdNwzXmjxdgb/Acs0/a3DmPZVIH0PbDr8I0hl2Ni4fCT8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tjepIxwy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="tjepIxwy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4E65C4CEC3; Tue, 10 Sep 2024 10:04:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1725962693; bh=196ycIMGKaN3v8nAAksoHcYeau6Mzn7Gx1SaW4EphN0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tjepIxwyxtbzfDU7E+zWKY79BXuMgTnt+2m3DYIltB6ovteR5NEHOKpEy6XoAiSLd kEnt+Uo59EnZjCbRQT2qIsATWlvJ4zH2RNRLVeGqAi5uVO8gzRk9W0y4MVxQ861hXg IjnwRdNgb1B7v1AIw3/+OHUQxe3DRwT2Ax/X2ToI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kent Overstreet , Sasha Levin Subject: [PATCH 5.4 092/121] lib/generic-radix-tree.c: Fix rare race in __genradix_ptr_alloc() Date: Tue, 10 Sep 2024 11:32:47 +0200 Message-ID: <20240910092550.222049709@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240910092545.737864202@linuxfoundation.org> References: <20240910092545.737864202@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ 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 f25eb111c051..34d3ac52de89 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