Fixed buffer overflow due to mistaking prog_size for cache_size

found by ajaybhargav

.travis.yml

@@ -139,7 +139,7 @@ jobs:
       install:
         - sudo apt-get install libfuse-dev
         - git clone --depth 1 https://github.com/geky/littlefs-fuse -b v2-alpha v2
-        - git clone --depth 1 https://github.com/geky/littlefs-fuse v1
+        - git clone --depth 1 https://github.com/geky/littlefs-fuse -b v1 v1
         - fusermount -V
         - gcc --version
       before_script:

lfs.c

@@ -29,7 +29,7 @@ static inline void lfs_cache_drop(lfs_t *lfs, lfs_cache_t *rcache) {
 
 static inline void lfs_cache_zero(lfs_t *lfs, lfs_cache_t *pcache) {
     // zero to avoid information leak
-    memset(pcache->buffer, 0xff, lfs->cfg->prog_size);
+    memset(pcache->buffer, 0xff, lfs->cfg->cache_size);
     pcache->block = 0xffffffff;
 }
 
@@ -2864,6 +2864,10 @@ int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) {
         return LFS_ERR_BADF;
     }
 
+    if (size > LFS_FILE_MAX) {
+        return LFS_ERR_INVAL;
+    }
+
     lfs_off_t oldsize = lfs_file_size(lfs, file);
     if (size < oldsize) {
         // need to flush since directly changing metadata

lfs.h

@@ -578,7 +578,8 @@ int lfs_dir_close(lfs_t *lfs, lfs_dir_t *dir);
 // Read an entry in the directory
 //
 // Fills out the info structure, based on the specified file or directory.
-// Returns a negative error code on failure.
+// Returns a positive value on success, 0 at the end of directory,
+// or a negative error code on failure.
 int lfs_dir_read(lfs_t *lfs, lfs_dir_t *dir, struct lfs_info *info);
 
 // Change the position of the directory