Squashfs: Compute expected length from inode size rather than block length
Previously in squashfs_readpage() when copying data into the page
cache, it used the length of the datablock read from the filesystem
(after decompression). However, if the filesystem has been corrupted
this data block may be short, which will leave pages unfilled.
The fix for this is to compute the expected number of bytes to copy
from the inode size, and use this to detect if the block is short.
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Tested-by: Willy Tarreau <w@1wt.eu>
Cc: Анатолий Тросиненко <anatoly.trosinenko@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index cce3060..f1c1430 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -431,10 +431,9 @@ void squashfs_copy_cache(struct page *page, struct squashfs_cache_entry *buffer,
}
/* Read datablock stored packed inside a fragment (tail-end packed block) */
-static int squashfs_readpage_fragment(struct page *page)
+static int squashfs_readpage_fragment(struct page *page, int expected)
{
struct inode *inode = page->mapping->host;
- struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
struct squashfs_cache_entry *buffer = squashfs_get_fragment(inode->i_sb,
squashfs_i(inode)->fragment_block,
squashfs_i(inode)->fragment_size);
@@ -445,23 +444,16 @@ static int squashfs_readpage_fragment(struct page *page)
squashfs_i(inode)->fragment_block,
squashfs_i(inode)->fragment_size);
else
- squashfs_copy_cache(page, buffer, i_size_read(inode) &
- (msblk->block_size - 1),
+ squashfs_copy_cache(page, buffer, expected,
squashfs_i(inode)->fragment_offset);
squashfs_cache_put(buffer);
return res;
}
-static int squashfs_readpage_sparse(struct page *page, int index, int file_end)
+static int squashfs_readpage_sparse(struct page *page, int expected)
{
- struct inode *inode = page->mapping->host;
- struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
- int bytes = index == file_end ?
- (i_size_read(inode) & (msblk->block_size - 1)) :
- msblk->block_size;
-
- squashfs_copy_cache(page, NULL, bytes, 0);
+ squashfs_copy_cache(page, NULL, expected, 0);
return 0;
}
@@ -471,6 +463,9 @@ static int squashfs_readpage(struct file *file, struct page *page)
struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
int index = page->index >> (msblk->block_log - PAGE_SHIFT);
int file_end = i_size_read(inode) >> msblk->block_log;
+ int expected = index == file_end ?
+ (i_size_read(inode) & (msblk->block_size - 1)) :
+ msblk->block_size;
int res;
void *pageaddr;
@@ -489,11 +484,11 @@ static int squashfs_readpage(struct file *file, struct page *page)
goto error_out;
if (bsize == 0)
- res = squashfs_readpage_sparse(page, index, file_end);
+ res = squashfs_readpage_sparse(page, expected);
else
- res = squashfs_readpage_block(page, block, bsize);
+ res = squashfs_readpage_block(page, block, bsize, expected);
} else
- res = squashfs_readpage_fragment(page);
+ res = squashfs_readpage_fragment(page, expected);
if (!res)
return 0;
