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 42EBF206F18; Tue, 8 Apr 2025 12:32:08 +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=1744115528; cv=none; b=Q/wi9CWUe5upUHZWyqR5oKeNqiCa6VjjG1ui4wEcNyCjlBCdqFf4DSbaCwr+8KGP5Y5QdLBvLlWwcFJuilbasQ9xkKYC6nSzkeUA/q85r2O0A02Tx1OjrQlpazCe8/E6dSD43WnSV6jfVOlEH3K1L6rArCQsZrJb9T/pSQ8z2+Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744115528; c=relaxed/simple; bh=zazv+dU2dB1iLQuLb1FjBrl89eWqzDkkOO39AamGbuE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=vC4/4m3vBK20kEjLuuql+62np6iB3guSMIDQV6LKUweyr5abrRW+gnhIZWO/5MdpxGYNkwchr5zqF294/wvASjY3mJJoDNgAf6bGxsDUln5a7da3f5aVHW4+ME+HEdrU5VvA9pOVjwHdQColUvqnD+mU2pZfr0Tj5RhZ0BrNdiM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=yod1SiC4; 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="yod1SiC4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3432C4CEE5; Tue, 8 Apr 2025 12:32:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1744115528; bh=zazv+dU2dB1iLQuLb1FjBrl89eWqzDkkOO39AamGbuE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yod1SiC4q19rdHNXFXuznf8/kzQBUkcntKAEctds++GUlBFoABf74XK6f0q2Sko+R LGspQT/hCVywPk6ltAZE7ZKRc7UWGF+bYPuegtsdZmSMJl7o1h+n+AkFNLUNd5y4vt BoIfzBVdjUhFi5e3XlQovDCv4zCJVC47D5Vm8644= 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 6.1 001/204] watch_queue: fix pipe accounting mismatch Date: Tue, 8 Apr 2025 12:48:51 +0200 Message-ID: <20250408104820.319109869@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250408104820.266892317@linuxfoundation.org> References: <20250408104820.266892317@linuxfoundation.org> User-Agent: quilt/0.68 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 6.1-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 442bb92212f2a..a72ea1c2f59fe 100644 --- a/kernel/watch_queue.c +++ b/kernel/watch_queue.c @@ -270,6 +270,15 @@ 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(sizeof(struct page *), nr_pages, GFP_KERNEL); if (!pages) -- 2.39.5