exfat: add a check for invalid data size

Add a check for invalid data size to avoid corrupted filesystem
from being further corrupted.

Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index 5b16181a4c2e9350ec0902a770b8efad9fef1cc8..8b30027d82512a5681c8e226b06758416ea3f054 100644 (file)
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -646,6 +646,11 @@ static int exfat_find(struct inode *dir, struct qstr *qname,
        info->valid_size = le64_to_cpu(ep2->dentry.stream.valid_size);
        info->size = le64_to_cpu(ep2->dentry.stream.size);
 
+       if (unlikely(EXFAT_B_TO_CLU_ROUND_UP(info->size, sbi) > sbi->used_clusters)) {
+               exfat_fs_error(sb, "data size is invalid(%lld)", info->size);
+               return -EIO;
+       }
+
        info->start_clu = le32_to_cpu(ep2->dentry.stream.start_clu);
        if (!is_valid_cluster(sbi, info->start_clu) && info->size) {
                exfat_warn(sb, "start_clu is invalid cluster(0x%x)",