From: Kir Kolyshkin <kolyshkin@gmail.com>
Date: Thu, 23 May 2024 21:12:10 +0000 (-0700)
Subject: [release-branch.go1.22] runtime: x_cgo_getstackbound: initialize pthread attr
X-Git-Tag: go1.22.4~3
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=95389d3d9d403f6a408258524556db0c629da049;p=gostls13.git

[release-branch.go1.22] runtime: x_cgo_getstackbound: initialize pthread attr

In glibc versions older than 2.32 (before commit 4721f95058),
pthread_getattr_np does not always initialize the `attr` argument,
and when it fails, it results in a NULL pointer dereference in
pthread_attr_destroy down the road.

This is the simplest way to avoid this, and an alternative to CL 585019.

Fixes #67650.

Change-Id: If490fd37020b03eb084ebbdbf9ae0248916426d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/587919
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/587979
Reviewed-by: Carlos Amedee <carlos@golang.org>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Commit-Queue: Matthew Dempsky <mdempsky@google.com>
---

diff --git a/src/runtime/cgo/gcc_stack_unix.c b/src/runtime/cgo/gcc_stack_unix.c
index f3fead9c9e..98a75a1967 100644
--- a/src/runtime/cgo/gcc_stack_unix.c
+++ b/src/runtime/cgo/gcc_stack_unix.c
@@ -18,6 +18,9 @@ x_cgo_getstackbound(uintptr bounds[2])
 	void *addr;
 	size_t size;
 
+	// Needed before pthread_getattr_np, too, since before glibc 2.32
+	// it did not call pthread_attr_init in all cases (see #65625).
+	pthread_attr_init(&attr);
 #if defined(__GLIBC__) || (defined(__sun) && !defined(__illumos__))
 	// pthread_getattr_np is a GNU extension supported in glibc.
 	// Solaris is not glibc but does support pthread_getattr_np
@@ -25,11 +28,9 @@ x_cgo_getstackbound(uintptr bounds[2])
 	pthread_getattr_np(pthread_self(), &attr);  // GNU extension
 	pthread_attr_getstack(&attr, &addr, &size); // low address
 #elif defined(__illumos__)
-	pthread_attr_init(&attr);
 	pthread_attr_get_np(pthread_self(), &attr);
 	pthread_attr_getstack(&attr, &addr, &size); // low address
 #else
-	pthread_attr_init(&attr);
 	pthread_attr_getstacksize(&attr, &size);
 	addr = __builtin_frame_address(0) + 4096 - size;
 #endif