[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, 15 insertions, 22 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 50774991f8d5..8ab3cf10d792 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -90,22 +90,13 @@ static mempool_t *nfs_commit_mempool;
 
 static DECLARE_WAIT_QUEUE_HEAD(nfs_write_congestion);
 
-struct nfs_write_data *nfs_commit_alloc(unsigned int pagecount)
+struct nfs_write_data *nfs_commit_alloc(void)
 {
         struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, SLAB_NOFS);
 
         if (p) {
                 memset(p, 0, sizeof(*p));
                 INIT_LIST_HEAD(&p->pages);
-                if (pagecount <= ARRAY_SIZE(p->page_array))
-                        p->pagevec = p->page_array;
-                else {
-                        p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
-                        if (!p->pagevec) {
-                                mempool_free(p, nfs_commit_mempool);
-                                p = NULL;
-                        }
-                }
         }
         return p;
 }
@@ -117,13 +108,15 @@ void nfs_commit_free(struct nfs_write_data *p)
         mempool_free(p, nfs_commit_mempool);
 }
 
-struct nfs_write_data *nfs_writedata_alloc(unsigned int pagecount)
+struct nfs_write_data *nfs_writedata_alloc(size_t len)
 {
+        unsigned int pagecount = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
         struct nfs_write_data *p = mempool_alloc(nfs_wdata_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 {
@@ -208,7 +201,7 @@ static int nfs_writepage_sync(struct nfs_open_context *ctx, struct inode *inode,
         int             result, written = 0;
         struct nfs_write_data *wdata;
 
-        wdata = nfs_writedata_alloc(1);
+        wdata = nfs_writedata_alloc(wsize);
         if (!wdata)
                 return -ENOMEM;
 
@@ -999,24 +992,24 @@ static int nfs_flush_multi(struct inode *inode, struct list_head *head, int how)
         struct nfs_page *req = nfs_list_entry(head->next);
         struct page *page = req->wb_page;
         struct nfs_write_data *data;
-        unsigned int wsize = NFS_SERVER(inode)->wsize;
-        unsigned int nbytes, offset;
+        size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
+        unsigned int offset;
         int requests = 0;
         LIST_HEAD(list);
 
         nfs_list_remove_request(req);
 
         nbytes = req->wb_bytes;
-        for (;;) {
-                data = nfs_writedata_alloc(1);
+        do {
+                size_t len = min(nbytes, wsize);
+
+                data = nfs_writedata_alloc(len);
                 if (!data)
                         goto out_bad;
                 list_add(&data->pages, &list);
                 requests++;
-                if (nbytes <= wsize)
-                        break;
-                nbytes -= wsize;
-        }
+                nbytes -= len;
+        } while (nbytes != 0);
         atomic_set(&req->wb_complete, requests);
 
         ClearPageError(page);
@@ -1070,7 +1063,7 @@ static int nfs_flush_one(struct inode *inode, struct list_head *head, int how)
         struct nfs_write_data   *data;
         unsigned int            count;
 
-        data = nfs_writedata_alloc(NFS_SERVER(inode)->wpages);
+        data = nfs_writedata_alloc(NFS_SERVER(inode)->wsize);
         if (!data)
                 goto out_bad;
 
@@ -1378,7 +1371,7 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how)
         struct nfs_write_data   *data;
         struct nfs_page         *req;
 
-        data = nfs_commit_alloc(NFS_SERVER(inode)->wpages);
+        data = nfs_commit_alloc();
 
         if (!data)
                 goto out_bad;