From: Weston Andros Adamson <dros@xxxxxxxxxxxxxxx>
commit bba5c1887a925a9945d22217d38d58d8b3ba1043 upstream.
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@xxxxxx>
Signed-off-by: Weston Andros Adamson <dros@xxxxxxxxxxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
fs/nfs/pagelist.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index f56b6351b660..91e84b3ad63e 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -734,10 +734,11 @@ 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))
@@ -745,12 +746,23 @@ 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)))
--
1.9.3
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