From patchwork Tue Feb 25 20:16:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ajay Kaher X-Patchwork-Id: 230559 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=-9.8 required=3.0 tests=DATE_IN_FUTURE_06_12, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 C1989C35DF5 for ; Tue, 25 Feb 2020 12:18:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9EA382176D for ; Tue, 25 Feb 2020 12:18:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729034AbgBYMSL (ORCPT ); Tue, 25 Feb 2020 07:18:11 -0500 Received: from ex13-edg-ou-001.vmware.com ([208.91.0.189]:59982 "EHLO EX13-EDG-OU-001.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726019AbgBYMSL (ORCPT ); Tue, 25 Feb 2020 07:18:11 -0500 Received: from sc9-mailhost3.vmware.com (10.113.161.73) by EX13-EDG-OU-001.vmware.com (10.113.208.155) with Microsoft SMTP Server id 15.0.1156.6; Tue, 25 Feb 2020 04:18:08 -0800 Received: from akaher-lnx-dev.eng.vmware.com (unknown [10.110.19.203]) by sc9-mailhost3.vmware.com (Postfix) with ESMTP id 0DD63408C1; Tue, 25 Feb 2020 04:18:02 -0800 (PST) From: Ajay Kaher To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v4 v4.4.y 7/7] fs: prevent page refcount overflow in pipe_buf_get Date: Wed, 26 Feb 2020 01:46:14 +0530 Message-ID: <1582661774-30925-8-git-send-email-akaher@vmware.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1582661774-30925-1-git-send-email-akaher@vmware.com> References: <1582661774-30925-1-git-send-email-akaher@vmware.com> MIME-Version: 1.0 Received-SPF: None (EX13-EDG-OU-001.vmware.com: akaher@vmware.com does not designate permitted sender hosts) 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 [ 4.4.y backport notes: Regarding the change in generic_pipe_buf_get(), note that page_cache_get() is the same as get_page(). See mainline commit 09cbfeaf1a5a6 "mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros" for context. ] Signed-off-by: Ajay Kaher Signed-off-by: Vlastimil Babka --- 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(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 36a5df9..16891f5 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -2031,10 +2031,8 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe, 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) { @@ -2052,7 +2050,9 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe, 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; @@ -2075,13 +2075,13 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe, ret = fuse_dev_do_write(fud, &cs, len); pipe_lock(pipe); +out_free: for (idx = 0; idx < nbuf; idx++) { struct pipe_buffer *buf = &bufs[idx]; buf->ops->release(pipe, buf); } pipe_unlock(pipe); -out: kfree(bufs); return ret; } diff --git a/fs/pipe.c b/fs/pipe.c index 1e7263b..6534470 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -178,9 +178,9 @@ 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) { - page_cache_get(buf->page); + return try_get_page(buf->page); } EXPORT_SYMBOL(generic_pipe_buf_get); diff --git a/fs/splice.c b/fs/splice.c index fde1263..57ccc58 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -1876,7 +1876,11 @@ 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; /* @@ -1948,7 +1952,11 @@ static int link_pipe(struct pipe_inode_info *ipipe, * 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; diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index 10876f3..0b28b65 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -112,18 +112,20 @@ 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); } /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual @@ -148,7 +150,7 @@ struct pipe_inode_info *alloc_pipe_info(void); 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 *); void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *); diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ae00e68..7fe8d04 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5731,12 +5731,16 @@ static void buffer_pipe_buf_release(struct pipe_inode_info *pipe, 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 (ref->ref > INT_MAX/2) + return false; + ref->ref++; + return true; } /* Pipe buffer operations for a buffer. */