AFS: Stop readlink() on AFS crashing due to NULL 'file' ptr (9886e836) · Commits · 戴 / test

kAFS crashes when asked to read a symbolic link because page_getlink() passes a NULL file pointer to read_mapping_page(), but afs_readpage() expects a file pointer from which to extract a key. Modify afs_readpage() to request the appropriate key from the calling process's keyrings if a file struct is not supplied with one attached. Signed-off-by:

David Howells <dhowells@redhat.com> Acked-by:

Anton Blanchard <anton@samba.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/afs/file.c

+15 −3

Original line number	Diff line number	Diff line
		@@ -134,9 +134,16 @@ static int afs_readpage(struct file file, struct page page)

		inode = page->mapping->host;

		ASSERT(file != NULL);
		if (file) {
		key = file->private_data;
		ASSERT(key != NULL);
		} else {
		key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
		if (IS_ERR(key)) {
		ret = PTR_ERR(key);
		goto error_nokey;
		}
		}

		_enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);

		@@ -207,12 +214,17 @@ static int afs_readpage(struct file file, struct page page)
		unlock_page(page);
		}

		if (!file)
		key_put(key);
		_leave(" = 0");
		return 0;

		error:
		SetPageError(page);
		unlock_page(page);
		if (!file)
		key_put(key);
		error_nokey:
		_leave(" = %d", ret);
		return ret;
		}

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