[PATCH 4.15 160/202] pipe: fix off-by-one error when checking buffer limits

4.15-stable review patch. If anyone has any objections, please let me know. -- From: Eric Biggers commit 9903a91c763ecdae333a04a9d89d79d2b8966503 upstream. With pipe-user-pages-hard set to 'N', users were actually only allowed up to 'N - 1' buffers; and

[PATCH 4.15 160/202] pipe: fix off-by-one error when checking buffer limits

4.15-stable review patch. If anyone has any objections, please let me know. -- From: Eric Biggers commit 9903a91c763ecdae333a04a9d89d79d2b8966503 upstream. With pipe-user-pages-hard set to 'N', users were actually only allowed up to 'N - 1' buffers; and likewise for