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New code for 5.6: 

- Fix an off-by-one error when checking if offset is within inode size
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Merge tag 'iomap-5.6-merge-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull iomap fix from Darrick Wong:
 "A single patch fixing an off-by-one error when we're checking to see
  how far we're gotten into an EOF page"

* tag 'iomap-5.6-merge-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  fs: Fix page_mkwrite off-by-one errors
This commit is contained in:
Linus Torvalds 2020-01-31 12:58:12 -08:00
parent 7eec11d3a7 243145bc43
commit 677b60dcb6
2 changed files with 33 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
fs/iomap/buffered-io.c
View File

@ -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,

28
include/linux/pagemap.h
View File

@ -636,4 +636,32 @@ static inline unsigned long dir_pages(struct inode *inode)
PAGE_SHIFT;
}
/**
* page_mkwrite_check_truncate - check if page was truncated
* @page: the page to check
* @inode: the inode to check the page against
*
* Returns the number of bytes in the page up to EOF,
* or -EFAULT if the page was truncated.
*/
static inline int page_mkwrite_check_truncate(struct page *page,
struct inode *inode)
{
loff_t size = i_size_read(inode);
pgoff_t index = size >> PAGE_SHIFT;
int offset = offset_in_page(size);
if (page->mapping != inode->i_mapping)
return -EFAULT;
/* page is wholly inside EOF */
if (page->index < index)
return PAGE_SIZE;
/* page is wholly past EOF */
if (page->index > index || !offset)
return -EFAULT;
/* page is partially inside EOF */
return offset;
}
#endif /* _LINUX_PAGEMAP_H */