From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, T_DKIMWL_WL_HIGH,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B689FC04AA9 for ; Thu, 2 May 2019 15:38:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 87E0221670 for ; Thu, 2 May 2019 15:38:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556811532; bh=iNONRk0BpK6qWzO3X/LCNFJaRhC85thhAG/OhEjBh5k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=tGxwW2Zb+1/TcGVChEbAdU7ql+czr64Jr8ZFric9SILUyOA7o/ds0w464WElj06Q/ 1XORYMhT8ko2CUuxdudfkag18Veav3Ki/CRTa/QZEAwmLsgKyKbKkrK5IwzdOY3qv/ 0mW4S6ahYsZJndsWnjY15Q1ZLuVw85vXFOX0KWGg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728083AbfEBP3w (ORCPT ); Thu, 2 May 2019 11:29:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:47830 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727824AbfEBP3s (ORCPT ); Thu, 2 May 2019 11:29:48 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A752821670; Thu, 2 May 2019 15:29:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556810987; bh=iNONRk0BpK6qWzO3X/LCNFJaRhC85thhAG/OhEjBh5k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GX7rAzxNCS9RGY4Iyvzdfu1YO3Em1TxDtdVKYtqlA6UGnlaeOAwVIHFHItlH8lUfI YntUqWtMzYUI4HDXdFH1vt+Vu4kBihN0QKnY0z7ygYHeIAPANC9o42oeUphjkiwmSp 6pAh6/ggkPn0fgJwNTRxFHh/jG4eze/wUkpoSk7M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn , Matthew Wilcox , stable@kernel.org, Linus Torvalds Subject: [PATCH 5.0 007/101] fs: prevent page refcount overflow in pipe_buf_get Date: Thu, 2 May 2019 17:20:09 +0200 Message-Id: <20190502143340.317389388@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190502143339.434882399@linuxfoundation.org> References: <20190502143339.434882399@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Matthew Wilcox commit 15fab63e1e57be9fdb5eec1bbc5916e9825e9acb upstream. Change pipe_buf_get() to return a bool indicating whether it succeeded in raising the refcount of the page (if the thing in the pipe is a page). This removes another mechanism for overflowing the page refcount. All callers converted to handle a failure. Reported-by: Jann Horn Signed-off-by: Matthew Wilcox Cc: stable@kernel.org Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/fuse/dev.c | 12 ++++++------ fs/pipe.c | 4 ++-- fs/splice.c | 12 ++++++++++-- include/linux/pipe_fs_i.h | 10 ++++++---- kernel/trace/trace.c | 6 +++++- 5 files changed, 29 insertions(+), 15 deletions(-) --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -2034,10 +2034,8 @@ static ssize_t fuse_dev_splice_write(str rem += pipe->bufs[(pipe->curbuf + idx) & (pipe->buffers - 1)].len; ret = -EINVAL; - if (rem < len) { - pipe_unlock(pipe); - goto out; - } + if (rem < len) + goto out_free; rem = len; while (rem) { @@ -2055,7 +2053,9 @@ static ssize_t fuse_dev_splice_write(str pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); pipe->nrbufs--; } else { - pipe_buf_get(pipe, ibuf); + if (!pipe_buf_get(pipe, ibuf)) + goto out_free; + *obuf = *ibuf; obuf->flags &= ~PIPE_BUF_FLAG_GIFT; obuf->len = rem; @@ -2078,11 +2078,11 @@ static ssize_t fuse_dev_splice_write(str ret = fuse_dev_do_write(fud, &cs, len); pipe_lock(pipe); +out_free: for (idx = 0; idx < nbuf; idx++) pipe_buf_release(pipe, &bufs[idx]); pipe_unlock(pipe); -out: kvfree(bufs); return ret; } --- a/fs/pipe.c +++ b/fs/pipe.c @@ -189,9 +189,9 @@ EXPORT_SYMBOL(generic_pipe_buf_steal); * in the tee() system call, when we duplicate the buffers in one * pipe into another. */ -void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) +bool generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { - get_page(buf->page); + return try_get_page(buf->page); } EXPORT_SYMBOL(generic_pipe_buf_get); --- a/fs/splice.c +++ b/fs/splice.c @@ -1588,7 +1588,11 @@ retry: * Get a reference to this pipe buffer, * so we can copy the contents over. */ - pipe_buf_get(ipipe, ibuf); + if (!pipe_buf_get(ipipe, ibuf)) { + if (ret == 0) + ret = -EFAULT; + break; + } *obuf = *ibuf; /* @@ -1662,7 +1666,11 @@ static int link_pipe(struct pipe_inode_i * Get a reference to this pipe buffer, * so we can copy the contents over. */ - pipe_buf_get(ipipe, ibuf); + if (!pipe_buf_get(ipipe, ibuf)) { + if (ret == 0) + ret = -EFAULT; + break; + } obuf = opipe->bufs + nbuf; *obuf = *ibuf; --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -108,18 +108,20 @@ struct pipe_buf_operations { /* * Get a reference to the pipe buffer. */ - void (*get)(struct pipe_inode_info *, struct pipe_buffer *); + bool (*get)(struct pipe_inode_info *, struct pipe_buffer *); }; /** * pipe_buf_get - get a reference to a pipe_buffer * @pipe: the pipe that the buffer belongs to * @buf: the buffer to get a reference to + * + * Return: %true if the reference was successfully obtained. */ -static inline void pipe_buf_get(struct pipe_inode_info *pipe, +static inline __must_check bool pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { - buf->ops->get(pipe, buf); + return buf->ops->get(pipe, buf); } /** @@ -178,7 +180,7 @@ struct pipe_inode_info *alloc_pipe_info( void free_pipe_info(struct pipe_inode_info *); /* Generic pipe buffer ops functions */ -void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); +bool generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *); int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *); int generic_pipe_buf_nosteal(struct pipe_inode_info *, struct pipe_buffer *); --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6843,12 +6843,16 @@ static void buffer_pipe_buf_release(stru buf->private = 0; } -static void buffer_pipe_buf_get(struct pipe_inode_info *pipe, +static bool buffer_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { struct buffer_ref *ref = (struct buffer_ref *)buf->private; + if (refcount_read(&ref->refcount) > INT_MAX/2) + return false; + refcount_inc(&ref->refcount); + return true; } /* Pipe buffer operations for a buffer. */