fs: ubifs: Fix UBIFS decompression on 64 bit

Add local size_t variable to crypto_comp_decompress as intermediate
storage for destination length to avoid memory corruption and incorrect
results on 64 bit targets.

This is what linux does for the various lz compression implementations.
Signed-off-by: NPaul Davey <paul.davey@alliedtelesis.co.nz>
Cc: Heiko Schocher <hs@denx.de>
Tested-by: NHeiko Schocher <hs@denx.de>

fs/ubifs/ubifs.c

@@ -125,6 +125,7 @@ crypto_comp_decompress(const struct ubifs_info *c, struct crypto_comp *tfm,
 {
 	struct ubifs_compressor *compr = ubifs_compressors[tfm->compressor];
 	int err;
+	size_t tmp_len = *dlen;
 
 	if (compr->compr_type == UBIFS_COMPR_NONE) {
 		memcpy(dst, src, slen);
@@ -132,11 +133,12 @@ crypto_comp_decompress(const struct ubifs_info *c, struct crypto_comp *tfm,
 		return 0;
 	}
 
-	err = compr->decompress(src, slen, dst, (size_t *)dlen);
+	err = compr->decompress(src, slen, dst, &tmp_len);
 	if (err)
 		ubifs_err(c, "cannot decompress %d bytes, compressor %s, "
 			  "error %d", slen, compr->name, err);
 
+	*dlen = tmp_len;
 	return err;
 
 	return 0;