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go: fix sigaction usage on i386 platforms

Browse Source 
In upstream the following commit [1] was submitted to resolve issues
with sigaction being used in linked libraries with cgo applications.

runtime: when using cgo on 386, call C sigaction function

This resolves potential segfaults with cgo applications that link to libraries
that intend to switch out signal handlers temporarily with sigaction.

[1] c5737dc21b

(From OE-Core rev: 1bc7a1731b218bb5c8a08c9823c777a40e17555e)

Signed-off-by: Randolph Sapp <rs@ti.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Randolph Sapp
2025-10-01 19:28:24 -05:00
committed by Richard Purdie
parent bb8aa3740f
commit cbf72b3696
2 changed files with 249 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
meta/recipes-devtools/go/go-1.25.0.inc
View File

@@ -16,5 +16,6 @@ SRC_URI += "\
file://0009-go-Filter-build-paths-on-staticly-linked-arches.patch \
file://0010-cmd-go-clear-GOROOT-for-func-ldShared-when-trimpath-.patch \
file://0011-cmd-link-stop-forcing-binutils-gold-dependency-on-aa.patch \
file://0001-runtime-when-using-cgo-on-386-call-C-sigaction-funct.patch \
"
SRC_URI[main.sha256sum] = "4bd01e91297207bfa450ea40d4d5a93b1b531a5e438473b2a06e18e077227225"

248
meta/recipes-devtools/go/go/0001-runtime-when-using-cgo-on-386-call-C-sigaction-funct.patch Normal file
View File

@@ -0,0 +1,248 @@
From c5737dc21bbac9fbefc35ac9313e66291d66b382 Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <iant@golang.org>
Date: Fri, 5 Sep 2025 22:24:37 -0700
Subject: [PATCH] runtime: when using cgo on 386, call C sigaction function
On 386 the C sigaction function assumes that the caller does not set
the SA_RESTORER flag. It does not copy the C sa_restorer field to
the kernel sa_restorer field. The effect is that the kernel sees
the SA_RESTORER flag but a NULL sa_restorer field, and the program
crashes when returning from a signal handler.
On the other hand, the C sigaction function will return the SA_RESTORER
flag and the sa_restorer field stored in the kernel.
This means that if the Go runtime installs a signal handler,
with SA_RESTORER as is required when calling the kernel,
and the Go program calls C code that calls the C sigaction function
to query the current signal handler, that C code will get a result
that it can't pass back to sigaction.
This CL fixes the problem by using the C sigaction function
for 386 programs that use cgo. This reuses the functionality
used on amd64 and other GOARCHs to support the race detector.
See #75253, or runtime/testdata/testprogcgo/eintr.go, for sample
code that used to fail on 386. No new test case is required,
we just remove the skip we used to have for eintr.go.
Fixes #75253
Change-Id: I803059b1fb9e09e9fbb43f68eccb6a59a92c2991
Reviewed-on: https://go-review.googlesource.com/c/go/+/701375
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Upstream-Status: Backport [https://github.com/golang/go/commit/c5737dc21bbac9fbefc35ac9313e66291d66b382]
Signed-off-by: Randolph Sapp <rs@ti.com>
---
src/runtime/cgo/gcc_sigaction.c | 8 ++++----
src/runtime/cgo/sigaction.go | 2 +-
src/runtime/cgo_sigaction.go | 6 +++++-
src/runtime/crash_cgo_test.go | 11 -----------
src/runtime/os_freebsd.go | 6 ++++++
src/runtime/os_linux.go | 18 +++++++++++++++++-
src/runtime/sigaction.go | 2 +-
src/runtime/sys_linux_386.s | 19 +++++++++++++++++++
8 files changed, 53 insertions(+), 19 deletions(-)
diff --git a/src/runtime/cgo/gcc_sigaction.c b/src/runtime/cgo/gcc_sigaction.c
index 7cbef7db11..ad48a88dc1 100644
--- a/src/runtime/cgo/gcc_sigaction.c
+++ b/src/runtime/cgo/gcc_sigaction.c
@@ -2,7 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-//go:build linux && (amd64 || arm64 || loong64 || ppc64le)
+//go:build linux && (386 || amd64 || arm64 || loong64 || ppc64le)
#include <errno.h>
#include <stddef.h>
@@ -17,7 +17,7 @@
// to and from struct sigaction — are specific to ${goos}/${goarch}.
typedef struct {
uintptr_t handler;
- uint64_t flags;
+ unsigned long flags;
#ifdef __loongarch__
uint64_t mask;
uintptr_t restorer;
@@ -57,7 +57,7 @@ x_cgo_sigaction(intptr_t signum, const go_sigaction_t *goact, go_sigaction_t *ol
sigaddset(&act.sa_mask, (int)(i+1));
}
}
- act.sa_flags = (int)(goact->flags & ~(uint64_t)SA_RESTORER);
+ act.sa_flags = (int)(goact->flags & ~(unsigned long)SA_RESTORER);
}
ret = sigaction((int)signum, goact ? &act : NULL, oldgoact ? &oldact : NULL);
@@ -79,7 +79,7 @@ x_cgo_sigaction(intptr_t signum, const go_sigaction_t *goact, go_sigaction_t *ol
oldgoact->mask |= (uint64_t)(1)<<i;
}
}
- oldgoact->flags = (uint64_t)oldact.sa_flags;
+ oldgoact->flags = (unsigned long)oldact.sa_flags;
}
_cgo_tsan_release();
diff --git a/src/runtime/cgo/sigaction.go b/src/runtime/cgo/sigaction.go
index dc3f5fd255..90034bad32 100644
--- a/src/runtime/cgo/sigaction.go
+++ b/src/runtime/cgo/sigaction.go
@@ -2,7 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-//go:build (linux && (amd64 || arm64 || loong64 || ppc64le)) || (freebsd && amd64)
+//go:build (linux && (386 || amd64 || arm64 || loong64 || ppc64le)) || (freebsd && amd64)
package cgo
diff --git a/src/runtime/cgo_sigaction.go b/src/runtime/cgo_sigaction.go
index 5c644587f0..f725dbef4d 100644
--- a/src/runtime/cgo_sigaction.go
+++ b/src/runtime/cgo_sigaction.go
@@ -3,8 +3,10 @@
// license that can be found in the LICENSE file.
// Support for sanitizers. See runtime/cgo/sigaction.go.
+// Also used on linux/386 to clear the SA_RESTORER flag
+// when using cgo; see issue #75253.
-//go:build (linux && (amd64 || arm64 || loong64 || ppc64le)) || (freebsd && amd64)
+//go:build (linux && (386 || amd64 || arm64 || loong64 || ppc64le)) || (freebsd && amd64)
package runtime
@@ -42,6 +44,8 @@ func sigaction(sig uint32, new, old *sigactiont) {
var ret int32
+ fixSigactionForCgo(new)
+
var g *g
if mainStarted {
g = getg()
diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go
index c5d7303261..b77ff8dafd 100644
--- a/src/runtime/crash_cgo_test.go
+++ b/src/runtime/crash_cgo_test.go
@@ -842,17 +842,6 @@ func TestEINTR(t *testing.T) {
switch runtime.GOOS {
case "plan9", "windows":
t.Skipf("no EINTR on %s", runtime.GOOS)
- case "linux":
- if runtime.GOARCH == "386" {
- // On linux-386 the Go signal handler sets
- // a restorer function that is not preserved
- // by the C sigaction call in the test,
- // causing the signal handler to crash when
- // returning the normal code. The test is not
- // architecture-specific, so just skip on 386
- // rather than doing a complicated workaround.
- t.Skip("skipping on linux-386; C sigaction does not preserve Go restorer")
- }
}
if runtime.GOOS == "freebsd" && race.Enabled {
t.Skipf("race + cgo freebsd not supported. See https://go.dev/issue/73788.")
diff --git a/src/runtime/os_freebsd.go b/src/runtime/os_freebsd.go
index ab859cfb47..68d895b95d 100644
--- a/src/runtime/os_freebsd.go
+++ b/src/runtime/os_freebsd.go
@@ -457,6 +457,12 @@ func sysSigaction(sig uint32, new, old *sigactiont) {
}
}
+// fixSigactionForCgo is needed for Linux.
+//
+//go:nosplit
+func fixSigactionForCgo(new *sigactiont) {
+}
+
// asmSigaction is implemented in assembly.
//
//go:noescape
diff --git a/src/runtime/os_linux.go b/src/runtime/os_linux.go
index c9d25a5be8..f9fe1b5f33 100644
--- a/src/runtime/os_linux.go
+++ b/src/runtime/os_linux.go
@@ -486,7 +486,8 @@ func setsig(i uint32, fn uintptr) {
sigfillset(&sa.sa_mask)
// Although Linux manpage says "sa_restorer element is obsolete and
// should not be used". x86_64 kernel requires it. Only use it on
- // x86.
+ // x86. Note that on 386 this is cleared when using the C sigaction
+ // function via cgo; see fixSigactionForCgo.
if GOARCH == "386" || GOARCH == "amd64" {
sa.sa_restorer = abi.FuncPCABI0(sigreturn__sigaction)
}
@@ -562,6 +563,21 @@ func sysSigaction(sig uint32, new, old *sigactiont) {
//go:noescape
func rt_sigaction(sig uintptr, new, old *sigactiont, size uintptr) int32
+// fixSigactionForCgo is called when we are using cgo to call the
+// C sigaction function. On 386 the C function does not expect the
+// SA_RESTORER flag to be set, and in some cases will fail if it is set:
+// it will pass the SA_RESTORER flag to the kernel without passing
+// the sa_restorer field. Since the C function will handle SA_RESTORER
+// for us, we need not pass it. See issue #75253.
+//
+//go:nosplit
+func fixSigactionForCgo(new *sigactiont) {
+ if GOARCH == "386" && new != nil {
+ new.sa_flags &^= _SA_RESTORER
+ new.sa_restorer = 0
+ }
+}
+
func getpid() int
func tgkill(tgid, tid, sig int)
diff --git a/src/runtime/sigaction.go b/src/runtime/sigaction.go
index 2027ae80bf..1a99f7f3ec 100644
--- a/src/runtime/sigaction.go
+++ b/src/runtime/sigaction.go
@@ -2,7 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-//go:build (linux && !amd64 && !arm64 && !loong64 && !ppc64le) || (freebsd && !amd64)
+//go:build (linux && !386 && !amd64 && !arm64 && !loong64 && !ppc64le) || (freebsd && !amd64)
package runtime
diff --git a/src/runtime/sys_linux_386.s b/src/runtime/sys_linux_386.s
index d53be243fe..8e832687e0 100644
--- a/src/runtime/sys_linux_386.s
+++ b/src/runtime/sys_linux_386.s
@@ -410,6 +410,25 @@ TEXT runtime·rt_sigaction(SB),NOSPLIT,$0
MOVL AX, ret+16(FP)
RET
+// Call the function stored in _cgo_sigaction using the GCC calling convention.
+TEXT runtime·callCgoSigaction(SB),NOSPLIT,$0-16
+ MOVL _cgo_sigaction(SB), AX
+ MOVL sig+0(FP), BX
+ MOVL new+4(FP), CX
+ MOVL old+8(FP), DX
+ MOVL SP, SI // align stack to call C function
+ SUBL $32, SP
+ ANDL $~15, SP
+ MOVL BX, 0(SP)
+ MOVL CX, 4(SP)
+ MOVL DX, 8(SP)
+ MOVL SI, 12(SP)
+ CALL AX
+ MOVL 12(SP), BX
+ MOVL BX, SP
+ MOVL AX, ret+12(FP)
+ RET
+
TEXT runtime·sigfwd(SB),NOSPLIT,$12-16
MOVL fn+0(FP), AX
MOVL sig+4(FP), BX
--
2.51.0