[release-branch.go1.15] cmd/link/internal/ld/pe: fix segfault adding resource section

The resource symbol may have been copied to the mmap'd
output buffer. If so, certain conditions can cause that
mmap'd output buffer to be munmap'd before we get a chance
to use it. To avoid any issues we copy the data to the heap
when the resource symbol exists.

Fixes #42384

Change-Id: I32ef5420802d7313a3d965b8badfbcfb9f0fba4a
GitHub-Last-Rev: 7b0f43011d06083ee3e871e48a87847636f738f9
GitHub-Pull-Request: golang/go#42427
Reviewed-on: https://go-review.googlesource.com/c/go/+/268018
Run-TryBot: Carlos Amedee <carlos@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Trust: Carlos Amedee <carlos@golang.org>

diff --git a/src/cmd/link/internal/ld/pe.go b/src/cmd/link/internal/ld/pe.go
index c9cb25dbe5b8b626180a1218451e2e7c179662e0..5d68ca7d9ca7728eec3e51f84842fcffb4b95464 100644 (file)
--- a/src/cmd/link/internal/ld/pe.go
+++ b/src/cmd/link/internal/ld/pe.go
@@ -1515,6 +1515,18 @@ func Asmbpe(ctxt *Link) {
        case sys.AMD64, sys.I386, sys.ARM:
        }
 
+       if rsrcsym != 0 {
+               // The resource symbol may have been copied to the mmap'd
+               // output buffer. If so, certain conditions can cause that
+               // mmap'd output buffer to be munmap'd before we get a chance
+               // to use it. To avoid any issues we copy the data to the heap
+               // when the resource symbol exists.
+               rsrc := ctxt.loader.Syms[rsrcsym]
+               data := make([]byte, len(rsrc.P))
+               copy(data, rsrc.P)
+               rsrc.P = data
+       }
+
        t := pefile.addSection(".text", int(Segtext.Length), int(Segtext.Length))
        t.characteristics = IMAGE_SCN_CNT_CODE | IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_EXECUTE | IMAGE_SCN_MEM_READ
        if ctxt.LinkMode == LinkExternal {