linux-kernel - [PATCH] tools: hv: hv_kvp_daemon: fix usage of realloc()

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Date:   Wed, 13 Sep 2017 20:41:02 +0200
From:   Martin Kepplinger <martink@...teo.de>
To:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com
Cc:     devel@...uxdriverproject.org, linux-kernel@...r.kernel.org,
        Martin Kepplinger <martink@...teo.de>
Subject: [PATCH] tools: hv: hv_kvp_daemon: fix usage of realloc()

realloc() returns NULL in case it fails. Since we don't save the
pointer in question elsewhere, we leak memory by assigning NULL
to the original memory in the heap.

realloc() doesn't free memory in case of failure, so let's do
it manually.

Signed-off-by: Martin Kepplinger <martink@...teo.de>
---
 tools/hv/hv_kvp_daemon.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/tools/hv/hv_kvp_daemon.c b/tools/hv/hv_kvp_daemon.c
index eaa3bec273c8..0b3b18d0a6e3 100644
--- a/tools/hv/hv_kvp_daemon.c
+++ b/tools/hv/hv_kvp_daemon.c
@@ -231,6 +231,7 @@ static int kvp_file_init(void)
 	size_t records_read;
 	char *fname;
 	struct kvp_record *record;
+	struct kvp_record *record_tmp;
 	struct kvp_record *readp;
 	int num_blocks;
 	int i;
@@ -284,12 +285,15 @@ static int kvp_file_init(void)
 				 * We have more data to read.
 				 */
 				num_blocks++;
-				record = realloc(record, alloc_unit *
+				record_tmp = realloc(record, alloc_unit *
 						num_blocks);
-				if (record == NULL) {
+				if (!record_tmp) {
+					free(record);
 					fclose(filep);
 					close(fd);
 					return 1;
+				} else {
+					record = record_tmp;
 				}
 				continue;
 			}
@@ -355,6 +359,7 @@ static int kvp_key_add_or_modify(int pool, const __u8 *key, int key_size,
 	int i;
 	int num_records;
 	struct kvp_record *record;
+	struct kvp_record *record_tmp;
 	int num_blocks;
 
 	if ((key_size > HV_KVP_EXCHANGE_MAX_KEY_SIZE) ||
@@ -387,11 +392,15 @@ static int kvp_key_add_or_modify(int pool, const __u8 *key, int key_size,
 	 */
 	if (num_records == (ENTRIES_PER_BLOCK * num_blocks)) {
 		/* Need to allocate a larger array for reg entries. */
-		record = realloc(record, sizeof(struct kvp_record) *
+		record_tmp = realloc(record, sizeof(struct kvp_record) *
 			 ENTRIES_PER_BLOCK * (num_blocks + 1));
 
-		if (record == NULL)
+		if (!record_tmp) {
+			free(record);
 			return 1;
+		} else {
+			record = record_tmp;
+		}
 		kvp_file_info[pool].num_blocks++;
 
 	}
-- 
2.11.0