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 8258C18FC9C; Tue, 10 Sep 2024 10:11:14 +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=1725963074; cv=none; b=kzDBiiG0Mbpa6grFaxLJjkniEZ+4ay41g9hpaXxk9sRBG6ykuj81PPXyS2P6PKRoz9udFmWcr/79vnyeBu+UUW6na6e0nDQwT9tYBtCrQmXLnQa2C2rT5LKZDDNAuPPey/hblzDJHUQlqXEV0zBMLL3qMdznvM11+oom/Tf78Pg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725963074; c=relaxed/simple; bh=8diSeC4mGxq6oJxB/ERH28E+5BzndmcZiF2LwRaV+Ow=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=u/S6Lyo8S8ercef+MJwTZlRQ7tuI+sfOufkOnViWkxJl59RVUGuafzcJgsBmc0QwXVXhI8REISiMaqti7un4Jogn8FFhHhwLXMjbfuty8nW93gPwqPqHHa1Jg5nwhfefDK3qFN01jTJ42Oi3MuCSx1jh6ZrSXH/XvLUnf4239XM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=K8HuT4w1; 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="K8HuT4w1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 09808C4CEC3; Tue, 10 Sep 2024 10:11:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1725963074; bh=8diSeC4mGxq6oJxB/ERH28E+5BzndmcZiF2LwRaV+Ow=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K8HuT4w1K8hts5l70AJnwjRuTw5/jtcYL1VEo+WFM5CSVgRKHbuvVpW0kKQWYHlBM qzIKuMbVyzU93CmpNVVsC1DgBq5WUQ5IrjEOrIMrmp2THEBrem0WedhVwqkJpD0cw3 5Qi+mbDV/KHL5mAtntPW4s+IWM7kUEGtngoPCQ1A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kent Overstreet , Sasha Levin Subject: [PATCH 6.1 126/192] lib/generic-radix-tree.c: Fix rare race in __genradix_ptr_alloc() Date: Tue, 10 Sep 2024 11:32:30 +0200 Message-ID: <20240910092603.206738044@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240910092557.876094467@linuxfoundation.org> References: <20240910092557.876094467@linuxfoundation.org> User-Agent: quilt/0.67 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: 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 7dfa88282b00..78f081d695d0 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