From 35f71f3cbd7d09dbc77764a3694bb0080ee0cb61 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Tue, 8 Dec 2020 18:29:02 -0500 Subject: [PATCH] xprtrdma: Fix XDRBUF_SPARSE_PAGES support commit 15261b9126cd5bb2ad8521da49d8f5c042d904c7 upstream. Olga K. observed that rpcrdma_marsh_req() allocates sparse pages only when it has determined that a Reply chunk is necessary. There are plenty of cases where no Reply chunk is needed, but the XDRBUF_SPARSE_PAGES flag is set. The result would be a crash in rpcrdma_inline_fixup() when it tries to copy parts of the received Reply into a missing page. To avoid crashing, handle sparse page allocation up front. Until XATTR support was added, this issue did not appear often because the only SPARSE_PAGES consumer always expected a reply large enough to always require a Reply chunk. Reported-by: Olga Kornievskaia Signed-off-by: Chuck Lever Cc: Signed-off-by: Trond Myklebust Signed-off-by: Greg Kroah-Hartman --- net/sunrpc/xprtrdma/rpc_rdma.c | 40 ++++++++++++++++++++++++++-------- 1 file changed, 31 insertions(+), 9 deletions(-) diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c index 0f5120c7668f..c48536f2121f 100644 --- a/net/sunrpc/xprtrdma/rpc_rdma.c +++ b/net/sunrpc/xprtrdma/rpc_rdma.c @@ -179,6 +179,31 @@ rpcrdma_nonpayload_inline(const struct rpcrdma_xprt *r_xprt, r_xprt->rx_ep->re_max_inline_recv; } +/* ACL likes to be lazy in allocating pages. For TCP, these + * pages can be allocated during receive processing. Not true + * for RDMA, which must always provision receive buffers + * up front. + */ +static noinline int +rpcrdma_alloc_sparse_pages(struct xdr_buf *buf) +{ + struct page **ppages; + int len; + + len = buf->page_len; + ppages = buf->pages + (buf->page_base >> PAGE_SHIFT); + while (len > 0) { + if (!*ppages) + *ppages = alloc_page(GFP_NOWAIT | __GFP_NOWARN); + if (!*ppages) + return -ENOBUFS; + ppages++; + len -= PAGE_SIZE; + } + + return 0; +} + /* Split @vec on page boundaries into SGEs. FMR registers pages, not * a byte range. Other modes coalesce these SGEs into a single MR * when they can. @@ -233,15 +258,6 @@ rpcrdma_convert_iovs(struct rpcrdma_xprt *r_xprt, struct xdr_buf *xdrbuf, ppages = xdrbuf->pages + (xdrbuf->page_base >> PAGE_SHIFT); page_base = offset_in_page(xdrbuf->page_base); while (len) { - /* ACL likes to be lazy in allocating pages - ACLs - * are small by default but can get huge. - */ - if (unlikely(xdrbuf->flags & XDRBUF_SPARSE_PAGES)) { - if (!*ppages) - *ppages = alloc_page(GFP_NOWAIT | __GFP_NOWARN); - if (!*ppages) - return -ENOBUFS; - } seg->mr_page = *ppages; seg->mr_offset = (char *)page_base; seg->mr_len = min_t(u32, PAGE_SIZE - page_base, len); @@ -867,6 +883,12 @@ rpcrdma_marshal_req(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst) __be32 *p; int ret; + if (unlikely(rqst->rq_rcv_buf.flags & XDRBUF_SPARSE_PAGES)) { + ret = rpcrdma_alloc_sparse_pages(&rqst->rq_rcv_buf); + if (ret) + return ret; + } + rpcrdma_set_xdrlen(&req->rl_hdrbuf, 0); xdr_init_encode(xdr, &req->rl_hdrbuf, rdmab_data(req->rl_rdmabuf), rqst);