From 6d1c0f3d28f98ea2736128ed3e46821496dc3a8c Mon Sep 17 00:00:00 2001 From: Anna Schumaker Date: Wed, 9 Jun 2021 17:07:29 -0400 Subject: sunrpc: Avoid a KASAN slab-out-of-bounds bug in xdr_set_page_base() This seems to happen fairly easily during READ_PLUS testing on NFS v4.2. I found that we could end up accessing xdr->buf->pages[pgnr] with a pgnr greater than the number of pages in the array. So let's just return early if we're setting base to a point at the end of the page data and let xdr_set_tail_base() handle setting up the buffer pointers instead. Signed-off-by: Anna Schumaker Fixes: 8d86e373b0ef ("SUNRPC: Clean up helpers xdr_set_iov() and xdr_set_page_base()") Signed-off-by: Trond Myklebust --- net/sunrpc/xdr.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'net') diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index 3964ff74ee51..ca10ba2626f2 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -1230,10 +1230,9 @@ static unsigned int xdr_set_page_base(struct xdr_stream *xdr, void *kaddr; maxlen = xdr->buf->page_len; - if (base >= maxlen) { - base = maxlen; - maxlen = 0; - } else + if (base >= maxlen) + return 0; + else maxlen -= base; if (len > maxlen) len = maxlen; -- cgit v1.2.3