From mboxrd@z Thu Jan 1 00:00:00 1970 From: Akinobu Mita Subject: [PATCH] bfs: fix bitmap size argument to find_first_zero_bit() Date: Wed, 2 Mar 2011 20:36:39 +0900 Message-ID: <1299065799-6289-1-git-send-email-akinobu.mita@gmail.com> Cc: Akinobu Mita , "Tigran A. Aivazian" , linux-fsdevel@vger.kernel.org To: linux-kernel@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org The usage of find_first_zero_bit() in bfs_create() is wrong for two reasons. The bitmap size argument to find_first_zero_bit() is info->si_lasti but the correct bitmap size is info->si_lasti + 1 as info->si_lasti is the last valid index in info->si_imap bitmap. Another problem is that it is impossible to detect that info->si_imap bitmap is full because there is an off-by-one bug in the return value check for find_first_zero_bit(). If no zero bits exist in info->si_imap, find_first_zero_bit() returns info->si_lasti. But the check can't catch it due to the off-by-one. Signed-off-by: Akinobu Mita Cc: "Tigran A. Aivazian" Cc: linux-fsdevel@vger.kernel.org --- fs/bfs/dir.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/fs/bfs/dir.c b/fs/bfs/dir.c index 685ecff..b14cebf 100644 --- a/fs/bfs/dir.c +++ b/fs/bfs/dir.c @@ -97,7 +97,7 @@ static int bfs_create(struct inode *dir, struct dentry *dentry, int mode, if (!inode) return -ENOSPC; mutex_lock(&info->bfs_lock); - ino = find_first_zero_bit(info->si_imap, info->si_lasti); + ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1); if (ino > info->si_lasti) { mutex_unlock(&info->bfs_lock); iput(inode); -- 1.7.4