From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukas Czerner Subject: [PATCH 3/4] fs: Remove i_size check from do_fallocate Date: Fri, 11 Apr 2014 20:57:44 +0200 Message-ID: <1397242665-2183-3-git-send-email-lczerner@redhat.com> References: <1397242665-2183-1-git-send-email-lczerner@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Lukas Czerner , ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org, xfs@oss.sgi.com To: linux-fsdevel@vger.kernel.org Return-path: In-Reply-To: <1397242665-2183-1-git-send-email-lczerner@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com List-Id: linux-ext4.vger.kernel.org Currently in do_fallocate in collapse range case we're checking whether offset + len is not bigger than i_size. However there is nothing which would prevent i_size from changing so the check is pointless. It should be done in the file system itself and the file system needs to make sure that i_size is not going to change. As it is now we can easily crash kernel by having two processes doing truncate and fallocate collapse range at the same time. This can be reproduced on ext4 and it is theoretically possible on xfs even though I was not able to trigger it with this simple test. This commit removes the check from do_fallocate and adds it to the file system. Signed-off-by: Lukas Czerner --- fs/ext4/extents.c | 11 +++++++++-- fs/open.c | 8 -------- fs/xfs/xfs_file.c | 10 +++++++++- 3 files changed, 18 insertions(+), 11 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 0177150..ff823b7 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -5364,8 +5364,6 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len) loff_t new_size; int ret; - BUG_ON(offset + len > i_size_read(inode)); - /* Collapse range works only on fs block size aligned offsets. */ if (offset & (EXT4_BLOCK_SIZE(sb) - 1) || len & (EXT4_BLOCK_SIZE(sb) - 1)) @@ -5387,6 +5385,15 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len) /* Take mutex lock */ mutex_lock(&inode->i_mutex); + /* + * There is no need to overlap collapse range with EOF, in which case + * it is effectively a truncate operation + */ + if (offset + len >= i_size_read(inode)) { + ret = -EINVAL; + goto out_mutex; + } + if (IS_SWAPFILE(inode)) { ret = -ETXTBSY; goto out_mutex; diff --git a/fs/open.c b/fs/open.c index 7882ff5..14af6be 100644 --- a/fs/open.c +++ b/fs/open.c @@ -287,14 +287,6 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len) if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0)) return -EFBIG; - /* - * There is no need to overlap collapse range with EOF, in which case - * it is effectively a truncate operation - */ - if ((mode & FALLOC_FL_COLLAPSE_RANGE) && - (offset + len >= i_size_read(inode))) - return -EINVAL; - if (!file->f_op->fallocate) return -EOPNOTSUPP; diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 003c005..4ba0ae9 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -840,7 +840,15 @@ xfs_file_fallocate( goto out_unlock; } - ASSERT(offset + len < i_size_read(inode)); + /* + * There is no need to overlap collapse range with EOF, + * in which case it is effectively a truncate operation + */ + if (offset + len >= i_size_read(inode)) { + error = -EINVAL; + goto out_unlock; + } + new_size = i_size_read(inode) - len; error = xfs_collapse_file_space(ip, offset, len); -- 1.8.3.1 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs