From 23fffa925ea2c9a2bcb1a4453e2c542635aa3545 Mon Sep 17 00:00:00 2001 From: Lukas Czerner Date: Sat, 12 Apr 2014 09:56:41 -0400 Subject: [PATCH] fs: move falloc collapse range check into the filesystem methods 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. The i_size check for the other fallocate modes are also done in the filesystems. As it is now we can easily crash the 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 Signed-off-by: "Theodore Ts'o" Acked-by: Dave Chinner Reviewed-by: Christoph Hellwig --- 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 ed4ec48..ac5460d 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -5368,8 +5368,6 @@ 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)) @@ -5398,6 +5396,15 @@ 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 3a83253..adf3420 100644 --- a/fs/open.c +++ b/fs/open.c @@ -284,14 +284,6 @@ 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 f7abff8..3cb528c 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); -- 2.7.4