From: Than McIntosh <thanm@google.com>
Date: Mon, 1 Jul 2024 16:11:33 +0000 (+0000)
Subject: cmd/link: align .reloc block starts by 32 bits for PE target
X-Git-Tag: go1.23rc2~2^2~31
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=f71c00b6165177dbcc5d40ff5f4731d297ee6090;p=gostls13.git

cmd/link: align .reloc block starts by 32 bits for PE target

Tweak the code that emits the PE ".reloc" section on Windows to ensure
that each relocation block is 32-bit aligned, which is required by the
PE standard.

Fixes #68260.

Change-Id: I39b75a7491b00fa97871aebb90d3be0ec09f9c40
Reviewed-on: https://go-review.googlesource.com/c/go/+/595896
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---

diff --git a/src/cmd/link/internal/ld/pe.go b/src/cmd/link/internal/ld/pe.go
index 8cfecafe84..14f0485530 100644
--- a/src/cmd/link/internal/ld/pe.go
+++ b/src/cmd/link/internal/ld/pe.go
@@ -1548,8 +1548,21 @@ func (rt *peBaseRelocTable) write(ctxt *Link) {
 	// sort the pages array
 	sort.Sort(rt.pages)
 
+	// .reloc section must be 32-bit aligned
+	if out.Offset()&3 != 0 {
+		Errorf(nil, "internal error, start of .reloc not 32-bit aligned")
+	}
+
 	for _, p := range rt.pages {
 		b := rt.blocks[p]
+
+		// Add a dummy entry at the end of the list if we have an
+		// odd number of entries, so as to ensure that the next
+		// block starts on a 32-bit boundary (see issue 68260).
+		if len(b.entries)&1 != 0 {
+			b.entries = append(b.entries, peBaseRelocEntry{})
+		}
+
 		const sizeOfPEbaseRelocBlock = 8 // 2 * sizeof(uint32)
 		blockSize := uint32(sizeOfPEbaseRelocBlock + len(b.entries)*2)
 		out.Write32(p)