From 89a3c9f5b9f0bcaa9aea3e8b2a616fcaea9aad78 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 25 Jun 2020 11:32:34 -0400 Subject: [PATCH] SUNRPC: Properly set the @subbuf parameter of xdr_buf_subsegment() @subbuf is an output parameter of xdr_buf_subsegment(). A survey of call sites shows that @subbuf is always uninitialized before xdr_buf_segment() is invoked by callers. There are some execution paths through xdr_buf_subsegment() that do not set all of the fields in @subbuf, leaving some pointer fields containing garbage addresses. Subsequent processing of that buffer then results in a page fault. Signed-off-by: Chuck Lever Cc: Signed-off-by: Anna Schumaker --- net/sunrpc/xdr.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index 6f7d82fb1eb0..be11d672b5b9 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -1118,6 +1118,7 @@ xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf, base = 0; } else { base -= buf->head[0].iov_len; + subbuf->head[0].iov_base = buf->head[0].iov_base; subbuf->head[0].iov_len = 0; } @@ -1130,6 +1131,8 @@ xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf, base = 0; } else { base -= buf->page_len; + subbuf->pages = buf->pages; + subbuf->page_base = 0; subbuf->page_len = 0; } @@ -1141,6 +1144,7 @@ xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf, base = 0; } else { base -= buf->tail[0].iov_len; + subbuf->tail[0].iov_base = buf->tail[0].iov_base; subbuf->tail[0].iov_len = 0; }