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 5A0931FBCB2; Tue, 8 Apr 2025 11:05:16 +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=1744110316; cv=none; b=PSIEtschjg0xxbB3euEus5pSs7XJdsQN8W7udezozNYZyW8SoPIMaZo5c9CehkS6KRw1184PSp7CPEEQ2XP61Pm41v0ciYFHC+Pa2JJiKEgqRhv0rflalb6FYKeypBVF+aePTf3VnMJ8UMzoAcB/hWjZ5UMlqIAEmfIx8P0imEs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744110316; c=relaxed/simple; bh=WDJDbuNbVdw2dUMSWog+TdB4QJMFd76hgPRIOe1lj4c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ovMfE7dv0gDUX8Wzh9JXmoCOFbQwtR0sFGct8hF29kf0cYbVQOvG036NexIAkZmiUdVGrKV7ZxF2bBrGyGts5dZtcFFQdiyykozaS22EzXTM0fs6QBJrUKzTktye7kwucLkXIJtr/GtoZtjU5eQ4ZNdc8V6UQI9FdkvlA0k+azY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=uj/i4ddX; 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="uj/i4ddX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D0E74C4CEE5; Tue, 8 Apr 2025 11:05:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1744110316; bh=WDJDbuNbVdw2dUMSWog+TdB4QJMFd76hgPRIOe1lj4c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uj/i4ddXs/KhgKaBYPvsjmEnR7pCxq1nEMlp3K3guflvV0GGVpgQk2c2H9jAjB6Y6 zF8R+dzr7t8i+CLnGJgpOQ+63j6kEloycWcyM6vQYBcAmpHgZnffpgpq6KiHR7RNpo NoDjYysWyCPExWKCGRQ+kDSvl1cwP5nafl7d0ZVk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Sandeen , Christian Brauner , Sasha Levin Subject: [PATCH 6.14 002/731] watch_queue: fix pipe accounting mismatch Date: Tue, 8 Apr 2025 12:38:19 +0200 Message-ID: <20250408104914.315087844@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250408104914.247897328@linuxfoundation.org> References: <20250408104914.247897328@linuxfoundation.org> User-Agent: quilt/0.68 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 6.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Sandeen [ Upstream commit f13abc1e8e1a3b7455511c4e122750127f6bc9b0 ] Currently, watch_queue_set_size() modifies the pipe buffers charged to user->pipe_bufs without updating the pipe->nr_accounted on the pipe itself, due to the if (!pipe_has_watch_queue()) test in pipe_resize_ring(). This means that when the pipe is ultimately freed, we decrement user->pipe_bufs by something other than what than we had charged to it, potentially leading to an underflow. This in turn can cause subsequent too_many_pipe_buffers_soft() tests to fail with -EPERM. To remedy this, explicitly account for the pipe usage in watch_queue_set_size() to match the number set via account_pipe_buffers() (It's unclear why watch_queue_set_size() does not update nr_accounted; it may be due to intentional overprovisioning in watch_queue_set_size()?) Fixes: e95aada4cb93d ("pipe: wakeup wr_wait after setting max_usage") Signed-off-by: Eric Sandeen Link: https://lore.kernel.org/r/206682a8-0604-49e5-8224-fdbe0c12b460@redhat.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- kernel/watch_queue.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c index 5267adeaa4034..41e4e8070923a 100644 --- a/kernel/watch_queue.c +++ b/kernel/watch_queue.c @@ -269,6 +269,15 @@ long watch_queue_set_size(struct pipe_inode_info *pipe, unsigned int nr_notes) if (ret < 0) goto error; + /* + * pipe_resize_ring() does not update nr_accounted for watch_queue + * pipes, because the above vastly overprovisions. Set nr_accounted on + * and max_usage this pipe to the number that was actually charged to + * the user above via account_pipe_buffers. + */ + pipe->max_usage = nr_pages; + pipe->nr_accounted = nr_pages; + ret = -ENOMEM; pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL); if (!pages) -- 2.39.5