Commit 0ebb9863 authored Jun 25, 2020 by Chuck Lever Committed by Sasha Levin Jun 30, 2020

SUNRPC: Properly set the @subbuf parameter of xdr_buf_subsegment()



commit 89a3c9f5b9f0bcaa9aea3e8b2a616fcaea9aad78 upstream.

@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 <chuck.lever@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 3c2f9ef9

net/sunrpc/xdr.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -1036,6 +1036,7 @@ 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;
		}

		@@ -1048,6 +1049,8 @@ 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;
		}

		@@ -1059,6 +1062,7 @@ 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;
		}