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 -b v1 v1
+        - git clone --depth 1 https://github.com/geky/littlefs-fuse 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;
 }
 
@@ -827,8 +827,7 @@ static lfs_stag_t lfs_dir_fetchmatch(lfs_t *lfs,
             // next commit not yet programmed or we're not in valid range
             if (!lfs_tag_isvalid(tag) ||
                     off + lfs_tag_dsize(tag) > lfs->cfg->block_size) {
-                dir->erased = (lfs_tag_type1(ptag) == LFS_TYPE_CRC &&
-                        dir->off % lfs->cfg->prog_size == 0);
+                dir->erased = (lfs_tag_type1(ptag) == LFS_TYPE_CRC);
                 break;
             }
 
@@ -855,7 +854,7 @@ static lfs_stag_t lfs_dir_fetchmatch(lfs_t *lfs,
                 }
 
                 // reset the next bit if we need to
-                ptag ^= (lfs_tag_chunk(tag) & 1U) << 31;
+                ptag ^= (lfs_tag_chunk(tag) & 1) << 31;
 
                 // toss our crc into the filesystem seed for
                 // pseudorandom numbers
@@ -1437,10 +1436,8 @@ static int lfs_dir_compact(lfs_t *lfs,
         // space is complicated, we need room for tail, crc, gstate,
         // cleanup delete, and we cap at half a block to give room
         // for metadata updates.
-        if (end - begin < 0xff &&
-                size <= lfs_min(lfs->cfg->block_size - 36,
-                    lfs_alignup(lfs->cfg->block_size/2,
-                        lfs->cfg->prog_size))) {
+        if (size <= lfs_min(lfs->cfg->block_size - 36,
+                lfs_alignup(lfs->cfg->block_size/2, lfs->cfg->prog_size))) {
             break;
         }
 
@@ -1500,7 +1497,7 @@ static int lfs_dir_compact(lfs_t *lfs,
 
     // begin loop to commit compaction to blocks until a compact sticks
     while (true) {
-        {
+        if (true) {
             // There's nothing special about our global delta, so feed it into
             // our local global delta
             int err = lfs_dir_getgstate(lfs, dir, &lfs->gdelta);
@@ -1599,12 +1596,13 @@ static int lfs_dir_compact(lfs_t *lfs,
             dir->count = end - begin;
             dir->off = commit.off;
             dir->etag = commit.ptag;
-            dir->erased = (dir->off % lfs->cfg->prog_size == 0);
+            dir->erased = true;
             // note we able to have already handled move here
             if (lfs_gstate_hasmovehere(&lfs->gpending, dir->pair)) {
                 lfs_gstate_xormove(&lfs->gpending,
                     &lfs->gpending, 0x3ff, NULL);
             }
+
         }
         break;
 
@@ -1713,7 +1711,7 @@ static int lfs_dir_commit(lfs_t *lfs, lfs_mdir_t *dir,
         }
     }
 
-    if (dir->erased || dir->count >= 0xff) {
+    if (dir->erased) {
         // try to commit
         struct lfs_commit commit = {
             .block = dir->pair[0],
@@ -2124,7 +2122,7 @@ static int lfs_ctz_extend(lfs_t *lfs,
         }
         LFS_ASSERT(nblock >= 2 && nblock <= lfs->cfg->block_count);
 
-        {
+        if (true) {
             err = lfs_bd_erase(lfs, nblock);
             if (err) {
                 if (err == LFS_ERR_CORRUPT) {
@@ -2383,8 +2381,7 @@ int lfs_file_opencfg(lfs_t *lfs, lfs_file_t *file,
         if (file->ctz.size > 0) {
             lfs_stag_t res = lfs_dir_get(lfs, &file->m,
                     LFS_MKTAG(0x700, 0x3ff, 0),
-                    LFS_MKTAG(LFS_TYPE_STRUCT, file->id,
-                        lfs_min(file->cache.size, 0x3fe)),
+                    LFS_MKTAG(LFS_TYPE_STRUCT, file->id, file->cache.size),
                     file->cache.buffer);
             if (res < 0) {
                 err = res;
@@ -2579,7 +2576,6 @@ int lfs_file_sync(lfs_t *lfs, lfs_file_t *file) {
     while (true) {
         int err = lfs_file_flush(lfs, file);
         if (err) {
-            file->flags |= LFS_F_ERRED;
             return err;
         }
 
@@ -2615,7 +2611,6 @@ int lfs_file_sync(lfs_t *lfs, lfs_file_t *file) {
                 if (err == LFS_ERR_NOSPC && (file->flags & LFS_F_INLINE)) {
                     goto relocate;
                 }
-                file->flags |= LFS_F_ERRED;
                 return err;
             }
 
@@ -2629,7 +2624,6 @@ relocate:
         file->off = file->pos;
         err = lfs_file_relocate(lfs, file);
         if (err) {
-            file->flags |= LFS_F_ERRED;
             return err;
         }
     }
@@ -2864,10 +2858,6 @@ 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
@@ -3233,9 +3223,8 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
     lfs_cache_zero(lfs, &lfs->pcache);
 
     // setup lookahead, must be multiple of 64-bits
+    LFS_ASSERT(lfs->cfg->lookahead_size % 8 == 0);
     LFS_ASSERT(lfs->cfg->lookahead_size > 0);
-    LFS_ASSERT(lfs->cfg->lookahead_size % 8 == 0 &&
-            (uintptr_t)lfs->cfg->lookahead_buffer % 8 == 0);
     if (lfs->cfg->lookahead_buffer) {
         lfs->free.buffer = lfs->cfg->lookahead_buffer;
     } else {
@@ -3303,7 +3292,7 @@ static int lfs_deinit(lfs_t *lfs) {
 
 int lfs_format(lfs_t *lfs, const struct lfs_config *cfg) {
     int err = 0;
-    {
+    if (true) {
         err = lfs_init(lfs, cfg);
         if (err) {
             return err;
@@ -4187,7 +4176,7 @@ static int lfs1_moved(lfs_t *lfs, const void *e) {
 static int lfs1_mount(lfs_t *lfs, struct lfs1 *lfs1,
         const struct lfs_config *cfg) {
     int err = 0;
-    {
+    if (true) {
         err = lfs_init(lfs, cfg);
         if (err) {
             return err;
@@ -4258,7 +4247,7 @@ int lfs_migrate(lfs_t *lfs, const struct lfs_config *cfg) {
         return err;
     }
 
-    {
+    if (true) {
         // iterate through each directory, copying over entries
         // into new directory
         lfs1_dir_t dir1;

lfs.h

@@ -215,9 +215,8 @@ struct lfs_config {
     // By default lfs_malloc is used to allocate this buffer.
     void *prog_buffer;
 
-    // Optional statically allocated lookahead buffer. Must be lookahead_size
-    // and aligned to a 64-bit boundary. By default lfs_malloc is used to
-    // allocate this buffer.
+    // Optional statically allocated program buffer. Must be lookahead_size.
+    // By default lfs_malloc is used to allocate this buffer.
     void *lookahead_buffer;
 
     // Optional upper limit on length of file names in bytes. No downside for
@@ -578,8 +577,7 @@ 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 positive value on success, 0 at the end of directory,
-// or a negative error code on failure.
+// Returns 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

lfs_util.h

@@ -192,7 +192,6 @@ static inline uint32_t lfs_tobe32(uint32_t a) {
 uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size);
 
 // Allocate memory, only used if buffers are not provided to littlefs
-// Note, memory must be 64-bit aligned
 static inline void *lfs_malloc(size_t size) {
 #ifndef LFS_NO_MALLOC
     return malloc(size);