1 files changed, 12 insertions, 7 deletions

diff --git a/fs/fat/cache.c b/fs/fat/cache.c
index e9bed49df6b7..78d501c1fb65 100644
--- a/fs/fat/cache.c
+++ b/fs/fat/cache.c
@@ -225,7 +225,8 @@ static inline void cache_init(struct fat_cache_id *cid, int fclus, int dclus)
 int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
 {
         struct super_block *sb = inode->i_sb;
-        const int limit = sb->s_maxbytes >> MSDOS_SB(sb)->cluster_bits;
+        struct msdos_sb_info *sbi = MSDOS_SB(sb);
+        const int limit = sb->s_maxbytes >> sbi->cluster_bits;
         struct fat_entry fatent;
         struct fat_cache_id cid;
         int nr;
@@ -234,6 +235,12 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
 
         *fclus = 0;
         *dclus = MSDOS_I(inode)->i_start;
+        if (!fat_valid_entry(sbi, *dclus)) {
+                fat_fs_error_ratelimit(sb,
+                        "%s: invalid start cluster (i_pos %lld, start %08x)",
+                        __func__, MSDOS_I(inode)->i_pos, *dclus);
+                return -EIO;
+        }
         if (cluster == 0)
                 return 0;
 
@@ -250,9 +257,8 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
                 /* prevent the infinite loop of cluster chain */
                 if (*fclus > limit) {
                         fat_fs_error_ratelimit(sb,
-                                        "%s: detected the cluster chain loop"
-                                        " (i_pos %lld)", __func__,
-                                        MSDOS_I(inode)->i_pos);
+                                "%s: detected the cluster chain loop (i_pos %lld)",
+                                __func__, MSDOS_I(inode)->i_pos);
                         nr = -EIO;
                         goto out;
                 }
@@ -262,9 +268,8 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
                         goto out;
                 else if (nr == FAT_ENT_FREE) {
                         fat_fs_error_ratelimit(sb,
-                                       "%s: invalid cluster chain (i_pos %lld)",
-                                       __func__,
-                                       MSDOS_I(inode)->i_pos);
+                                "%s: invalid cluster chain (i_pos %lld)",
+                                __func__, MSDOS_I(inode)->i_pos);
                         nr = -EIO;
                         goto out;
                 } else if (nr == FAT_ENT_EOF) {