From 4aed7a192332cb6a975f135b256c193034332677 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Mon, 28 Jun 2021 16:41:17 +0200
Subject: [PATCH] openssl: avoid static variable for seed flag

Avoid the race condition risk by instead storing the "seeded" flag in
the multi handle. Modern OpenSSL versions handle the seeding itself so
doing the seeding once per multi-handle instead of once per process is
less of an issue.

Reported-by: Gerrit Renker
Fixes #7296
Closes #7306
---
 lib/multihandle.h  | 3 +++
 lib/vtls/openssl.c | 9 ++++-----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/lib/multihandle.h b/lib/multihandle.h
index 96b84749fc..2e4a6ffba5 100644
--- a/lib/multihandle.h
+++ b/lib/multihandle.h
@@ -153,6 +153,9 @@ struct Curl_multi {
   bool recheckstate; /* see Curl_multi_connchanged */
   bool in_callback;            /* true while executing a callback */
   bool ipv6_works;
+#ifdef USE_OPENSSL
+  bool ssl_seeded;
+#endif
 };
 
 #endif /* HEADER_CURL_MULTIHANDLE_H */
diff --git a/lib/vtls/openssl.c b/lib/vtls/openssl.c
index e4aa26ac1f..52dbf5f3eb 100644
--- a/lib/vtls/openssl.c
+++ b/lib/vtls/openssl.c
@@ -435,17 +435,16 @@ static bool rand_enough(void)
 
 static CURLcode ossl_seed(struct Curl_easy *data)
 {
-  /* we have the "SSL is seeded" boolean static to prevent multiple
-     time-consuming seedings in vain */
-  static bool ssl_seeded = FALSE;
   char fname[256];
 
-  if(ssl_seeded)
+  /* This might get called before it has been added to a multi handle */
+  if(data->multi && data->multi->ssl_seeded)
     return CURLE_OK;
 
   if(rand_enough()) {
     /* OpenSSL 1.1.0+ will return here */
-    ssl_seeded = TRUE;
+    if(data->multi)
+      data->multi->ssl_seeded = TRUE;
     return CURLE_OK;
   }