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authorAndreas Gruenbacher <agruenba@redhat.com>2020-01-06 08:58:23 -0800
committerDarrick J. Wong <darrick.wong@oracle.com>2020-01-06 08:58:23 -0800
commit243145bc4336684c69f95de0a303b31f2e5bf264 (patch)
tree1a5bf570c07209e01f80c93118d0e960545b697d /fs/iomap
parentfd6988496e79a6a4bdb514a4655d2920209eb85d (diff)
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.c18
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,