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 9C30D264FA0; Tue, 8 Apr 2025 10:59:05 +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=1744109945; cv=none; b=YID7/d3HH1PFFmFhWticQWYW5U0lx/13oPnYYtl9X1CqOu6CGoIrxZ2gH0IOTbbM2hZ/xcZnmSIe3RkQQZQeueOgX5SspPE5x/Im4dbPaMpVnu7miu7MIFcc7TIQd2t8wauTdKeLiG8Q50mUPY5dwGsG1Bsd6KwMmrKG4fAvEi4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744109945; c=relaxed/simple; bh=vgLnIe7rIoz8cuJT9xuMPdD7FPwzKGKr49BP/d7ls0Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Cw3nkNWtFED4ROUoydNODlAVt4XaIle34qmyEf0K3KvwPN8XL+M4fUAlzwmUW3M1jVdoOxX+uExyqimNCZ5278VQ7iURMLpshpUb9eRgT6PxlDBn1Z9lKLUjn6hWseMj4YRHBGrCnq7u5jRCv50YbWifjJzbPbxEZWL/S/0iJpM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BXL02gHo; 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="BXL02gHo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A2BCC4CEE5; Tue, 8 Apr 2025 10:59:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1744109945; bh=vgLnIe7rIoz8cuJT9xuMPdD7FPwzKGKr49BP/d7ls0Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BXL02gHoyMV2LD09zpC1gPbduFCb0X6FrmenBNADIvF+OvkVn3cMKFE88bp4Azclr 7kCQK9ZoAc1a5Xkkep17wHFSkuBxZzDWsThLUnHalL9i9AYTL0oFDvF0wVgFGs3NKa 9nFCxYlhzwZVDazp+DxX48jc+Z7ZXMhXbfxPWYyo= 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 5.10 111/227] watch_queue: fix pipe accounting mismatch Date: Tue, 8 Apr 2025 12:48:09 +0200 Message-ID: <20250408104823.679577697@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250408104820.353768086@linuxfoundation.org> References: <20250408104820.353768086@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 5.10-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 73717917d8164..37da8647b4ecb 100644 --- a/kernel/watch_queue.c +++ b/kernel/watch_queue.c @@ -274,6 +274,15 @@ 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