libceph: fix corruption when using page_count 0 page in rbd (178eda29) · Commits · 戴 / test

It has been reported that using ZFSonLinux on rbd will result in memory corruption. The bug report can be found here: https://github.com/zfsonlinux/spl/issues/241 http://tracker.ceph.com/issues/7790 The reason is that ZFS will send pages with page_count 0 into rbd, which in turns send them to tcp_sendpage. However, tcp_sendpage cannot deal with page_count 0, as it will do get_page and put_page, and erroneously free the page. This type of issue has been noted before, and handled in iscsi, drbd, etc. So, rbd should also handle this. This fix address this issue by fall back to slower sendmsg when page_count 0 detected. Cc: Sage Weil <sage@inktank.com> Cc: Yehuda Sadeh <yehuda@inktank.com> Cc: stable@vger.kernel.org Signed-off-by:

Chunwei Chen <tuxoko@gmail.com> Reviewed-by:

Ilya Dryomov <ilya.dryomov@inktank.com>

net/ceph/messenger.c

+19 −1

Original line number	Diff line number	Diff line
		@@ -557,7 +557,7 @@ static int ceph_tcp_sendmsg(struct socket sock, struct kvec iov,
		return r;
		}

		static int ceph_tcp_sendpage(struct socket sock, struct page page,
		static int __ceph_tcp_sendpage(struct socket sock, struct page page,
		int offset, size_t size, bool more)
		{
		int flags = MSG_DONTWAIT \| MSG_NOSIGNAL \| (more ? MSG_MORE : MSG_EOR);
		@@ -570,6 +570,24 @@ static int ceph_tcp_sendpage(struct socket sock, struct page page,
		return ret;
		}

		static int ceph_tcp_sendpage(struct socket sock, struct page page,
		int offset, size_t size, bool more)
		{
		int ret;
		struct kvec iov;

		/* sendpage cannot properly handle pages with page_count == 0,
		* we need to fallback to sendmsg if that's the case */
		if (page_count(page) >= 1)
		return __ceph_tcp_sendpage(sock, page, offset, size, more);

		iov.iov_base = kmap(page) + offset;
		iov.iov_len = size;
		ret = ceph_tcp_sendmsg(sock, &iov, 1, size, more);
		kunmap(page);

		return ret;
		}

		/*
		* Shutdown/close the socket for the given connection.

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