From ec9a44b2a59a9061e1979be5268dd657cd5402fd Mon Sep 17 00:00:00 2001
From: LemonBoy <thatlemon@gmail.com>
Date: Thu, 20 May 2021 15:28:59 +0200
Subject: [PATCH] std: Make atfork handler more robust

The atfork handler is executed even when fork()-ing threads that have
never initialized their local csprng. Handle this case gracefully
instead of raising a runtime error.

Fixes #8841
---
 lib/std/crypto/tlcsprng.zig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/std/crypto/tlcsprng.zig b/lib/std/crypto/tlcsprng.zig
index c23e99e2dd..c2cb119d4a 100644
--- a/lib/std/crypto/tlcsprng.zig
+++ b/lib/std/crypto/tlcsprng.zig
@@ -150,6 +150,9 @@ fn setupPthreadAtforkAndFill(buffer: []u8) void {
 }
 
 fn childAtForkHandler() callconv(.C) void {
+    // The atfork handler is global, this function may be called after
+    // fork()-ing threads that never initialized the CSPRNG context.
+    if (wipe_mem.len == 0) return;
     std.crypto.utils.secureZero(u8, wipe_mem);
 }