From 67fad106a219e083c91c79695bd1807dde1bf7b9 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Wed, 12 Dec 2012 11:38:44 -0500 Subject: [PATCH] nfs: don't zero out the rest of the page if we hit the EOF on a DIO READ Eryu provided a test program that would segfault when attempting to read past the EOF on file that was opened O_DIRECT. The buffer given to the read() call was on the stack, and when he attempted to read past it it would scribble over the rest of the stack page. If we hit the end of the file on a DIO READ request, then we don't want to zero out the rest of the buffer. These aren't pagecache pages after all, and there's no guarantee that the buffers that were passed in represent entire pages. Cc: # v3.5+ Cc: Fred Isaman Reported-by: Eryu Guan Signed-off-by: Jeff Layton Signed-off-by: Trond Myklebust --- fs/nfs/direct.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c index cae26cb..594f4e7 100644 --- a/fs/nfs/direct.c +++ b/fs/nfs/direct.c @@ -266,14 +266,6 @@ static void nfs_direct_read_completion(struct nfs_pgio_header *hdr) struct nfs_page *req = nfs_list_entry(hdr->pages.next); struct page *page = req->wb_page; - if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { - if (bytes > hdr->good_bytes) - zero_user(page, 0, PAGE_SIZE); - else if (hdr->good_bytes - bytes < PAGE_SIZE) - zero_user_segment(page, - hdr->good_bytes & ~PAGE_MASK, - PAGE_SIZE); - } if (!PageCompound(page)) { if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { if (bytes < hdr->good_bytes) -- 2.7.4