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authorWeston Andros Adamson <dros@primarydata.com>2014-08-14 17:39:32 -0400
committerTrond Myklebust <trond.myklebust@primarydata.com>2014-08-22 18:04:44 -0400
commitbba5c1887a925a9945d22217d38d58d8b3ba1043 (patch)
tree9326421cb1b32538ae194287eb0614faf7f50089 /fs
parent7c3af975257383ece54b83c0505d3e0656cb7daf (diff)
downloadlinux-stericsson-bba5c1887a925a9945d22217d38d58d8b3ba1043.tar.gz
nfs: disallow duplicate pages in pgio page vectors
Adjacent requests that share the same page are allowed, but should only use one entry in the page vector. This avoids overruning the page vector - it is sized based on how many bytes there are, not by request count. This fixes issues that manifest as "Redzone overwritten" bugs (the vector overrun) and hangs waiting on page read / write, as it waits on the same page more than once. This also adds bounds checking to the page vector with a graceful failure (WARN_ON_ONCE and pgio error returned to application). Reported-by: Toralf Förster <toralf.foerster@gmx.de> Signed-off-by: Weston Andros Adamson <dros@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/nfs/pagelist.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 4ec67f8d70aa..a1d1de7b97c5 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -724,10 +724,11 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
struct nfs_pgio_header *hdr)
{
struct nfs_page *req;
- struct page **pages;
+ struct page **pages,
+ *last_page;
struct list_head *head = &desc->pg_list;
struct nfs_commit_info cinfo;
- unsigned int pagecount;
+ unsigned int pagecount, pageused;
pagecount = nfs_page_array_len(desc->pg_base, desc->pg_count);
if (!nfs_pgarray_set(&hdr->page_array, pagecount))
@@ -735,12 +736,23 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
pages = hdr->page_array.pagevec;
+ last_page = NULL;
+ pageused = 0;
while (!list_empty(head)) {
req = nfs_list_entry(head->next);
nfs_list_remove_request(req);
nfs_list_add_request(req, &hdr->pages);
- *pages++ = req->wb_page;
+
+ if (WARN_ON_ONCE(pageused >= pagecount))
+ return nfs_pgio_error(desc, hdr);
+
+ if (!last_page || last_page != req->wb_page) {
+ *pages++ = last_page = req->wb_page;
+ pageused++;
+ }
}
+ if (WARN_ON_ONCE(pageused != pagecount))
+ return nfs_pgio_error(desc, hdr);
if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
(desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))