diff options
| author |   Andreas Gruenbacher <agruenba@redhat.com> | 2020-01-06 08:58:23 -0800 |
|---|---|---|
| committer |   Darrick J. Wong <darrick.wong@oracle.com> | 2020-01-06 08:58:23 -0800 |
| commit | 243145bc4336684c69f95de0a303b31f2e5bf264 (patch) | |
| tree | 1a5bf570c07209e01f80c93118d0e960545b697d /fs/iomap | |
| parent | Linux 5.5-rc4 (diff) | |
| download | wireguard-linux-243145bc4336684c69f95de0a303b31f2e5bf264.tar.xz wireguard-linux-243145bc4336684c69f95de0a303b31f2e5bf264.zip | |
fs: Fix page_mkwrite off-by-one errors
The check in block_page_mkwrite that is meant to determine whether an
offset is within the inode size is off by one. This bug has been copied
into iomap_page_mkwrite and several filesystems (ubifs, ext4, f2fs,
ceph).
Fix that by introducing a new page_mkwrite_check_truncate helper that
checks for truncate and computes the bytes in the page up to EOF. Use
the helper in iomap.
NOTE from Darrick: The original patch fixed a number of filesystems, but
then there were merge conflicts with the f2fs for-next tree; a
subsequent re-submission of the patch had different btrfs changes with
no explanation; and Christoph complained that each per-fs fix should be
a separate patch. In my view that's too much risk to take on, so I
decided to drop all the hunks except for iomap, since I've actually QA'd
XFS.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
[darrick: drop everything but the iomap parts]
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/iomap')
| -rw-r--r-- | fs/iomap/buffered-io.c | 18 |
1 files changed, 5 insertions, 13 deletions
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 828444e14d09..7c84c4c027c4 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1077,24 +1077,16 @@ vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops) struct page *page = vmf->page; struct inode *inode = file_inode(vmf->vma->vm_file); unsigned long length; - loff_t offset, size; + loff_t offset; ssize_t ret; lock_page(page); - size = i_size_read(inode); - offset = page_offset(page); - if (page->mapping != inode->i_mapping || offset > size) { - /* We overload EFAULT to mean page got truncated */ - ret = -EFAULT; + ret = page_mkwrite_check_truncate(page, inode); + if (ret < 0) goto out_unlock; - } - - /* page is wholly or partially inside EOF */ - if (offset > size - PAGE_SIZE) - length = offset_in_page(size); - else - length = PAGE_SIZE; + length = ret; + offset = page_offset(page); while (length > 0) { ret = iomap_apply(inode, offset, length, IOMAP_WRITE | IOMAP_FAULT, ops, page, |