[PATCH] NFS: large non-page-aligned direct I/O clobbers memory

The logic in nfs_direct_read_schedule and nfs_direct_write_schedule can
allow data->npages to be one larger than rpages.  This causes a page
pointer to be written beyond the end of the pagevec in nfs_read_data (or
nfs_write_data).

Fix this by making nfs_(read|write)_alloc() calculate the size of the
pagevec array, and initialise data->npages.

Also get rid of the redundant argument to nfs_commit_alloc().

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 13 insertions, 11 deletions

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index da9cf11c326..7a9ee00e0c6 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -43,13 +43,15 @@ static mempool_t *nfs_rdata_mempool;
 
 #define MIN_POOL_READ	(32)
 
-struct nfs_read_data *nfs_readdata_alloc(unsigned int pagecount)
+struct nfs_read_data *nfs_readdata_alloc(size_t len)
 {
+	unsigned int pagecount = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	struct nfs_read_data *p = mempool_alloc(nfs_rdata_mempool, SLAB_NOFS);
 
 	if (p) {
 		memset(p, 0, sizeof(*p));
 		INIT_LIST_HEAD(&p->pages);
+		p->npages = pagecount;
 		if (pagecount <= ARRAY_SIZE(p->page_array))
 			p->pagevec = p->page_array;
 		else {
@@ -140,7 +142,7 @@ static int nfs_readpage_sync(struct nfs_open_context *ctx, struct inode *inode,
 	int		result;
 	struct nfs_read_data *rdata;
 
-	rdata = nfs_readdata_alloc(1);
+	rdata = nfs_readdata_alloc(count);
 	if (!rdata)
 		return -ENOMEM;
 
@@ -336,25 +338,25 @@ static int nfs_pagein_multi(struct list_head *head, struct inode *inode)
 	struct nfs_page *req = nfs_list_entry(head->next);
 	struct page *page = req->wb_page;
 	struct nfs_read_data *data;
-	unsigned int rsize = NFS_SERVER(inode)->rsize;
-	unsigned int nbytes, offset;
+	size_t rsize = NFS_SERVER(inode)->rsize, nbytes;
+	unsigned int offset;
 	int requests = 0;
 	LIST_HEAD(list);
 
 	nfs_list_remove_request(req);
 
 	nbytes = req->wb_bytes;
-	for(;;) {
-		data = nfs_readdata_alloc(1);
+	do {
+		size_t len = min(nbytes,rsize);
+
+		data = nfs_readdata_alloc(len);
 		if (!data)
 			goto out_bad;
 		INIT_LIST_HEAD(&data->pages);
 		list_add(&data->pages, &list);
 		requests++;
-		if (nbytes <= rsize)
-			break;
-		nbytes -= rsize;
-	}
+		nbytes -= len;
+	} while(nbytes != 0);
 	atomic_set(&req->wb_complete, requests);
 
 	ClearPageError(page);
@@ -402,7 +404,7 @@ static int nfs_pagein_one(struct list_head *head, struct inode *inode)
 	if (NFS_SERVER(inode)->rsize < PAGE_CACHE_SIZE)
 		return nfs_pagein_multi(head, inode);
 
-	data = nfs_readdata_alloc(NFS_SERVER(inode)->rpages);
+	data = nfs_readdata_alloc(NFS_SERVER(inode)->rsize);
 	if (!data)
 		goto out_bad;