From 4867cb2a5489f9987cfad66478dd63c87f634477 Mon Sep 17 00:00:00 2001
From: Oran Agra <[email protected]>
Date: Mon, 4 Oct 2021 12:10:17 +0300
Subject: [PATCH] Fix redis-cli / redis-sential overflow on some platforms
  (CVE-2021-32762) (#9587)

The redis-cli command line tool and redis-sentinel service may be vulnerable to integer overflow when parsing specially crafted large multi-bulk network replies. This is a result of a vulnerability in the underl ying hiredis library which does not perform an overflow check before calling the calloc()heap allocation function.

This issue only impacts systems with heap allocators that do not perform their own overflow checks. Most modern systems do and are therefore not likely to be affected. Furthermore, by default redis-sentinel uses the jemalloc allocator which is also not vulnerable.

Co-authored-by: Yossi Gottlieb <[email protected]>
---
 deps/hiredis/hiredis.c |  1 +
 deps/hiredis/test.c    | 14 ++++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/deps/hiredis/hiredis.c b/deps/hiredis/hiredis.c
index abd94c0..bda2ffd 100644
--- a/deps/hiredis/hiredis.c
+++ b/deps/hiredis/hiredis.c
@@ -168,6 +168,7 @@ static void *createArrayObject(const redisReadTask *task, size_t elements) {
         return NULL;
 
     if (elements > 0) {
+	 if (SIZE_MAX / sizeof(redisReply*) < elements) return NULL;  /* Don't overflow */
         r->element = calloc(elements,sizeof(redisReply*));
         if (r->element == NULL) {
             freeReplyObject(r);
diff --git a/deps/hiredis/test.c b/deps/hiredis/test.c
index 8668e18..9760862 100644
--- a/deps/hiredis/test.c
+++ b/deps/hiredis/test.c
@@ -400,6 +400,20 @@ static void test_reply_reader(void) {
     freeReplyObject(reply);
     redisReaderFree(reader);
 
+    test("Multi-bulk never overflows regardless of maxelements: ");
+    size_t bad_mbulk_len = (SIZE_MAX / sizeof(void *)) + 3;
+    char bad_mbulk_reply[100];
+    snprintf(bad_mbulk_reply, sizeof(bad_mbulk_reply), "*%llu\r\n+asdf\r\n",
+        (unsigned long long) bad_mbulk_len);
+
+    reader = redisReaderCreate();
+    reader->maxelements = 0;    /* Don't rely on default limit */
+    redisReaderFeed(reader, bad_mbulk_reply, strlen(bad_mbulk_reply));
+    ret = redisReaderGetReply(reader,&reply);
+    test_cond(ret == REDIS_ERR && strcasecmp(reader->errstr, "Out of memory") == 0);
+    freeReplyObject(reply);
+    redisReaderFree(reader);
+
 #if LLONG_MAX > SIZE_MAX
     test("Set error when array > SIZE_MAX: ");
     reader = redisReaderCreate();
-- 
2.27.0