Looks like there are still cases when "space_left - frag1bytes" can legitimately exceed PAGE_SIZE. Ensure that xdr->end always remains within the current encode buffer. Reported-by: Bruce Fields <bfields@xxxxxxxxxxxx> Reported-by: Zorro Lang <zlang@xxxxxxxxxx> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216151 Fixes: 6c254bf3b637 ("SUNRPC: Fix the calculation of xdr->end in xdr_get_next_encode_buffer()") Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> --- net/sunrpc/xdr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Hi- I had a few minutes yesterday afternoon to look into this one. The following one-liner seems to address the issue and passes my smoke tests with NFSv4.1/TCP and NFSv3/RDMA. Any thoughts? diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index f87a2d8f23a7..916659be2774 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -987,7 +987,7 @@ static noinline __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr, if (space_left - nbytes >= PAGE_SIZE) xdr->end = p + PAGE_SIZE; else - xdr->end = p + space_left - frag1bytes; + xdr->end = p + min_t(int, space_left - frag1bytes, PAGE_SIZE); xdr->buf->page_len += frag2bytes; xdr->buf->len += nbytes;
