SUNRPC: Fix READ_PLUS crasher

commit a23dd544debcda4ee4a549ec7de59e85c3c8345c upstream.

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@fieldses.org>
Reported-by: Zorro Lang <zlang@redhat.com>
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@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Chuck Lever 2022-06-30 16:48:18 -04:00 committed by Greg Kroah-Hartman
parent ed03a650fb
commit 6a0b9512a6

View File

@ -752,7 +752,7 @@ static __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
*/ */
xdr->p = (void *)p + frag2bytes; xdr->p = (void *)p + frag2bytes;
space_left = xdr->buf->buflen - xdr->buf->len; space_left = xdr->buf->buflen - xdr->buf->len;
if (space_left - nbytes >= PAGE_SIZE) if (space_left - frag1bytes >= PAGE_SIZE)
xdr->end = (void *)p + PAGE_SIZE; xdr->end = (void *)p + PAGE_SIZE;
else else
xdr->end = (void *)p + space_left - frag1bytes; xdr->end = (void *)p + space_left - frag1bytes;