fs/squashfs: Fix Coverity Scan defects

Fix control flow issues and null pointer dereferences.
Signed-off-by: NJoao Marcos Costa <jmcosta944@gmail.com>

fs/squashfs/sqfs.c

@@ -154,7 +154,7 @@ static int sqfs_frag_lookup(u32 inode_fragment_index,
 	header = get_unaligned_le16(metadata_buffer + table_offset);
 	metadata = metadata_buffer + table_offset + SQFS_HEADER_SIZE;
 
-	if (!metadata) {
+	if (!metadata || !header) {
 		ret = -ENOMEM;
 		goto free_buffer;
 	}
@@ -434,9 +434,9 @@ static int sqfs_search_dir(struct squashfs_dir_stream *dirs, char **token_list,
 {
 	struct squashfs_super_block *sblk = ctxt.sblk;
 	char *path, *target, **sym_tokens, *res, *rem;
-	struct squashfs_ldir_inode *ldir = NULL;
 	int j, ret, new_inode_number, offset;
 	struct squashfs_symlink_inode *sym;
+	struct squashfs_ldir_inode *ldir;
 	struct squashfs_dir_inode *dir;
 	struct fs_dir_stream *dirsp;
 	struct fs_dirent *dent;
@@ -448,8 +448,8 @@ static int sqfs_search_dir(struct squashfs_dir_stream *dirs, char **token_list,
 	table = sqfs_find_inode(dirs->inode_table, le32_to_cpu(sblk->inodes),
 				sblk->inodes, sblk->block_size);
 
-	/* root is a regular directory, not an extended one */
 	dir = (struct squashfs_dir_inode *)table;
+	ldir = (struct squashfs_ldir_inode *)table;
 
 	/* get directory offset in directory table */
 	offset = sqfs_dir_offset(table, m_list, m_count);
@@ -1146,7 +1146,10 @@ static int sqfs_get_regfile_info(struct squashfs_reg_inode *reg,
 	finfo->start = get_unaligned_le32(&reg->start_block);
 	finfo->frag = SQFS_IS_FRAGMENTED(get_unaligned_le32(&reg->fragment));
 
-	if (finfo->size < 1 || finfo->offset < 0 || finfo->start < 0)
+	if (finfo->frag && finfo->offset == 0xFFFFFFFF)
+		return -EINVAL;
+
+	if (finfo->size < 1 || finfo->start == 0xFFFFFFFF)
 		return -EINVAL;
 
 	if (finfo->frag) {
@@ -1156,7 +1159,7 @@ static int sqfs_get_regfile_info(struct squashfs_reg_inode *reg,
 		if (ret < 0)
 			return -EINVAL;
 		finfo->comp = true;
-		if (fentry->size < 1 || fentry->start < 0)
+		if (fentry->size < 1 || fentry->start == 0x7FFFFFFF)
 			return -EINVAL;
 	} else {
 		datablk_count = DIV_ROUND_UP(finfo->size, le32_to_cpu(blksz));
@@ -1181,7 +1184,10 @@ static int sqfs_get_lregfile_info(struct squashfs_lreg_inode *lreg,
 	finfo->start = get_unaligned_le64(&lreg->start_block);
 	finfo->frag = SQFS_IS_FRAGMENTED(get_unaligned_le32(&lreg->fragment));
 
-	if (finfo->size < 1 || finfo->offset < 0 || finfo->start < 0)
+	if (finfo->frag && finfo->offset == 0xFFFFFFFF)
+		return -EINVAL;
+
+	if (finfo->size < 1 || finfo->start == 0x7FFFFFFF)
 		return -EINVAL;
 
 	if (finfo->frag) {
@@ -1191,7 +1197,7 @@ static int sqfs_get_lregfile_info(struct squashfs_lreg_inode *lreg,
 		if (ret < 0)
 			return -EINVAL;
 		finfo->comp = true;
-		if (fentry->size < 1 || fentry->start < 0)
+		if (fentry->size < 1 || fentry->start == 0x7FFFFFFF)
 			return -EINVAL;
 	} else {
 		datablk_count = DIV_ROUND_UP(finfo->size, le32_to_cpu(blksz));

fs/squashfs/sqfs_dir.c

@@ -34,8 +34,7 @@ int sqfs_dir_offset(void *dir_i, u32 *m_list, int m_count)
 	struct squashfs_ldir_inode *ldir;
 	struct squashfs_dir_inode *dir;
 	u32 start_block;
-	u16 offset;
-	int j;
+	int j, offset;
 
 	switch (get_unaligned_le16(&base->inode_type)) {
 	case SQFS_DIR_TYPE:

fs/squashfs/sqfs_inode.c

@@ -142,8 +142,11 @@ int sqfs_read_metablock(unsigned char *file_mapping, int offset,
 	u16 header;
 
 	data = file_mapping + offset;
+	if (!data)
+		return -EFAULT;
+
 	header = get_unaligned((u16 *)data);
-	if (!header || !data)
+	if (!header)
 		return -EINVAL;
 
 	*compressed = SQFS_COMPRESSED_METADATA(header);