From 11b08a75cd6b93473d0ab6e4b6a94247ee341a01 Mon Sep 17 00:00:00 2001
From: Cherry Mui <cherryyz@google.com>
Date: Fri, 15 Sep 2023 12:02:01 -0400
Subject: [PATCH] cmd/link: reject invalid -R flag

Reject -R value that is not a power of 2, or less than 4K.

Fixes #62660.

Change-Id: I3fa33c23c25311a93c0accc9acbd1e465789b8c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/528715
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---
 src/cmd/link/internal/ld/main.go | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/cmd/link/internal/ld/main.go b/src/cmd/link/internal/ld/main.go
index b978cfc7d4..589b5065fd 100644
--- a/src/cmd/link/internal/ld/main.go
+++ b/src/cmd/link/internal/ld/main.go
@@ -236,6 +236,13 @@ func Main(arch *sys.Arch, theArch Arch) {
 		Exitf("dynamic linking required on %s; -d flag cannot be used", buildcfg.GOOS)
 	}
 
+	isPowerOfTwo := func(n int64) bool {
+		return n > 0 && n&(n-1) == 0
+	}
+	if *FlagRound != -1 && (*FlagRound < 4096 || !isPowerOfTwo(*FlagRound)) {
+		Exitf("invalid -R value 0x%x", *FlagRound)
+	}
+
 	checkStrictDups = *FlagStrictDups
 
 	switch flagW {
-- 
2.51.0