[PATCH] smbfs chroot issue (CVE-2006-1864)

[linux-2.6-omap-h63xx.git] / fs / splice.c

diff --git a/fs/splice.c b/fs/splice.c
index 7fb04970c72d853e53874e4ec03d9df48911dcb3..a285fd746dc0d34aa97762a6e138416acae292e7 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -51,7 +51,7 @@ struct splice_pipe_desc {
  * addition of remove_mapping(). If success is returned, the caller may
  * attempt to reuse this page for another destination.
  */
-static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
+static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
                                     struct pipe_buffer *buf)
 {
        struct page *page = buf->page;
@@ -78,16 +78,18 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
                return 1;
        }
 
+       buf->flags |= PIPE_BUF_FLAG_LRU;
        return 0;
 }
 
-static void page_cache_pipe_buf_release(struct pipe_inode_info *info,
+static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
                                        struct pipe_buffer *buf)
 {
        page_cache_release(buf->page);
+       buf->flags &= ~PIPE_BUF_FLAG_LRU;
 }
 
-static int page_cache_pipe_buf_pin(struct pipe_inode_info *info,
+static int page_cache_pipe_buf_pin(struct pipe_inode_info *pipe,
                                   struct pipe_buffer *buf)
 {
        struct page *page = buf->page;
@@ -141,6 +143,7 @@ static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
        if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
                return 1;
 
+       buf->flags |= PIPE_BUF_FLAG_LRU;
        return generic_pipe_buf_steal(pipe, buf);
 }
 
@@ -321,6 +324,8 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
                                              mapping_gfp_mask(mapping));
                        if (unlikely(error)) {
                                page_cache_release(page);
+                               if (error == -EEXIST)
+                                       continue;
                                break;
                        }
                        /*
@@ -497,14 +502,14 @@ EXPORT_SYMBOL(generic_file_splice_read);
  * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
  * using sendpage(). Return the number of bytes sent.
  */
-static int pipe_to_sendpage(struct pipe_inode_info *info,
+static int pipe_to_sendpage(struct pipe_inode_info *pipe,
                            struct pipe_buffer *buf, struct splice_desc *sd)
 {
        struct file *file = sd->file;
        loff_t pos = sd->pos;
        int ret, more;
 
-       ret = buf->ops->pin(info, buf);
+       ret = buf->ops->pin(pipe, buf);
        if (!ret) {
                more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
 
@@ -535,7 +540,7 @@ static int pipe_to_sendpage(struct pipe_inode_info *info,
  * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
  * a new page in the output file page cache and fill/dirty that.
  */
-static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
+static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
                        struct splice_desc *sd)
 {
        struct file *file = sd->file;
@@ -549,7 +554,7 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
        /*
         * make sure the data in this buffer is uptodate
         */
-       ret = buf->ops->pin(info, buf);
+       ret = buf->ops->pin(pipe, buf);
        if (unlikely(ret))
                return ret;
 
@@ -566,37 +571,23 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
         */
        if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) {
                /*
-                * If steal succeeds, buf->page is now pruned from the vm
-                * side (page cache) and we can reuse it. The page will also
-                * be locked on successful return.
+                * If steal succeeds, buf->page is now pruned from the
+                * pagecache and we can reuse it. The page will also be
+                * locked on successful return.
                 */
-               if (buf->ops->steal(info, buf))
+               if (buf->ops->steal(pipe, buf))
                        goto find_page;
 
                page = buf->page;
-               page_cache_get(page);
-
-               /*
-                * page must be on the LRU for adding to the pagecache.
-                * Check this without grabbing the zone lock, if it isn't
-                * the do grab the zone lock, recheck, and add if necessary.
-                */
-               if (!PageLRU(page)) {
-                       struct zone *zone = page_zone(page);
-
-                       spin_lock_irq(&zone->lru_lock);
-                       if (!PageLRU(page)) {
-                               SetPageLRU(page);
-                               add_page_to_inactive_list(zone, page);
-                       }
-                       spin_unlock_irq(&zone->lru_lock);
-               }
-
                if (add_to_page_cache(page, mapping, index, gfp_mask)) {
-                       page_cache_release(page);
                        unlock_page(page);
                        goto find_page;
                }
+
+               page_cache_get(page);
+
+               if (!(buf->flags & PIPE_BUF_FLAG_LRU))
+                       lru_cache_add(page);
        } else {
 find_page:
                page = find_lock_page(mapping, index);
@@ -647,23 +638,36 @@ find_page:
        }
 
        ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len);
-       if (ret == AOP_TRUNCATED_PAGE) {
+       if (unlikely(ret)) {
+               loff_t isize = i_size_read(mapping->host);
+
+               if (ret != AOP_TRUNCATED_PAGE)
+                       unlock_page(page);
                page_cache_release(page);
-               goto find_page;
-       } else if (ret)
+               if (ret == AOP_TRUNCATED_PAGE)
+                       goto find_page;
+
+               /*
+                * prepare_write() may have instantiated a few blocks
+                * outside i_size.  Trim these off again.
+                */
+               if (sd->pos + this_len > isize)
+                       vmtruncate(mapping->host, isize);
+
                goto out;
+       }
 
        if (buf->page != page) {
                /*
                 * Careful, ->map() uses KM_USER0!
                 */
-               char *src = buf->ops->map(info, buf, 1);
+               char *src = buf->ops->map(pipe, buf, 1);
                char *dst = kmap_atomic(page, KM_USER1);
 
                memcpy(dst + offset, src + buf->offset, this_len);
                flush_dcache_page(page);
                kunmap_atomic(dst, KM_USER1);
-               buf->ops->unmap(info, buf, src);
+               buf->ops->unmap(pipe, buf, src);
        }
 
        ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len);