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 B246722257E; Tue, 8 Apr 2025 11:50:30 +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=1744113030; cv=none; b=G0MH9vhAx0kRZ8ARgw0eamo4xS1f//kMMPBaNQs1MK/yvxebxBzOERPNydbTnd1VeciqsQAbmmDSk4Yo7a2ltd+RM18UBRv87/e8tFFmc8+/4Vzato/7JxvqLlBpN3hbwBHk9Mh+KxyrgoyK6/fy4dOMlZqOHDwAKmSvjmHEl9Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744113030; c=relaxed/simple; bh=qFxQk2CENdizXND+4TUHV2iKE18cWyFuTa/QyjDDkbg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WMtpFuLhlALP1U2kCLa5L/vQwk61PbYSkh3Sh66nopVZOz/AoGNjAe1O2i0f7HF9JNsAFRz0unY8zCvK+ncAEXLhYyg+QzkfW4fFXy6BLIAgRAXHvSUAgeKbulBRPnmxUVqixvGpkblPx6XP5CgZy5rL5iqUQhXmlXXFPsdW06k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Esc6U9mV; 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="Esc6U9mV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42302C4CEE5; Tue, 8 Apr 2025 11:50:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1744113030; bh=qFxQk2CENdizXND+4TUHV2iKE18cWyFuTa/QyjDDkbg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Esc6U9mVSOMjJCAaRfEzmd1o4cAyHFNALg3LRxQS0vAZcpQBSZo79FFnGwIVDwb1d kkAYav9pbUgb38Qv5JgHUD9yXMapYVlG4zSo1cZl3SMTJ07S/zZbjamp7bfAKmtkS7 QoX5JTgoiDC6yyV2DuY7O6SvqPhgyni9B0daH+6s= 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 6.6 001/268] watch_queue: fix pipe accounting mismatch Date: Tue, 8 Apr 2025 12:46:52 +0200 Message-ID: <20250408104828.541965412@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250408104828.499967190@linuxfoundation.org> References: <20250408104828.499967190@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 6.6-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 778b4056700ff..17254597accd4 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(sizeof(struct page *), nr_pages, GFP_KERNEL); if (!pages) -- 2.39.5