From 4c0421fa6df136ff869a078594b4b7b7637e566a Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 27 Feb 2023 13:04:54 +0000 Subject: [PATCH] iov: Fix netfs_extract_user_to_sg() Fix the loop check in netfs_extract_user_to_sg() for extraction from user-backed iterators to do the body if npages > 0, not if npages < 0 (which it can never be). This isn't currently used by cifs, which only ever extracts data from BVEC, KVEC and XARRAY iterators at this level, user-backed iterators having being decanted into BVEC iterators at a higher level to accommodate the work being done in a kernel thread. Found by smatch: fs/netfs/iterator.c:139 netfs_extract_user_to_sg() warn: unsigned 'npages' is never less than zero. Fixes: 018584697533 ("netfs: Add a function to extract an iterator into a scatterlist") Reported-by: kernel test robot Link: https://lore.kernel.org/oe-kbuild-all/202302261115.P3TQi1ZO-lkp@intel.com/ Reported-by: Dan Carpenter Link: https://lore.kernel.org/r/Y/yYnAhoAYDBKixX@kili Reviewed-by: Paulo Alcantara (SUSE) Signed-off-by: David Howells cc: Jeff Layton cc: linux-cifs@vger.kernel.org cc: linux-cachefs@redhat.com Signed-off-by: Steve French --- fs/netfs/iterator.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/netfs/iterator.c b/fs/netfs/iterator.c index f00d43b..e9a45de 100644 --- a/fs/netfs/iterator.c +++ b/fs/netfs/iterator.c @@ -134,7 +134,7 @@ static ssize_t netfs_extract_user_to_sg(struct iov_iter *iter, npages = DIV_ROUND_UP(off + len, PAGE_SIZE); sg_max -= npages; - for (; npages < 0; npages--) { + for (; npages > 0; npages--) { struct page *page = *pages; size_t seg = min_t(size_t, PAGE_SIZE - off, len); -- 2.7.4