TestUpdateDevices fails on i386

[kolyshkin]

Description

We have a CI job to compile runc and run its unit tests to make sure the code is 32-bit clean.

Recently (about a month ago) TestUpdateDevices and/or TestUpdateDevicesSystemd start to fail randomly.

The failure is happening in one of two ways:

1. invalid character 'ÿ' looking for beginning of object key string

Log

``` === RUN TestUpdateDevicesSystemd ....... time="2024-12-23T02:28:15Z" level=info msg="found more than one filter (2) attached to a cgroup -- removing extra filters!" time="2024-12-23T02:28:15Z" level=info msg="removing old filter 0 from cgroup" id=1028 name= run_count=0 runtime=0s tag=531db05b114e9af3 type=CGroupDevice time="2024-12-23T02:28:15Z" level=info msg="removing old filter 1 from cgroup" id=1029 name= run_count=0 runtime=0s tag=a04f5eef06a7f555 type=CGroupDevice time="2024-12-23T02:28:15Z" level=info msg="found more than one filter (2) attached to a cgroup -- removing extra filters!" time="2024-12-23T02:28:15Z" level=info msg="removing old filter 0 from cgroup" id=1030 name= run_count=0 runtime=0s tag=fb6cb1c301453333 type=CGroupDevice time="2024-12-23T02:28:15Z" level=info msg="removing old filter 1 from cgroup" id=1031 name= run_count=0 runtime=0s tag=3b0b81b071f088cd type=CGroupDevice update_test.go:67: unexpected error: unable to start container process: invalid character 'ÿ' looking for beginning of object key string --- FAIL: TestUpdateDevicesSystemd (3.03s) ```

2. panic in strings.Contains

Log

``` .... time="2025-01-16T04:13:05Z" level=info msg="removing old filter 0 from cgroup" id=824 name= run_count=0 runtime=0s tag=531db05b114e9af3 type=CGroupDevice time="2025-01-16T04:13:05Z" level=info msg="removing old filter 1 from cgroup" id=825 name= run_count=0 runtime=0s tag=a04f5eef06a7f555 type=CGroupDevice time="2025-01-16T04:13:05Z" level=info msg="found more than one filter (2) attached to a cgroup -- removing extra filters!" time="2025-01-16T04:13:05Z" level=info msg="removing old filter 0 from cgroup" id=826 name= run_count=0 runtime=0s tag=fb6cb1c301453333 type=CGroupDevice time="2025-01-16T04:13:05Z" level=info msg="removing old filter 1 from cgroup" id=827 name= run_count=0 runtime=0s tag=3b0b81b071f088cd type=CGroupDevice unexpected fault address 0xffffffff fatal error: fault [signal SIGSEGV: segmentation violation code=0x1 addr=0xffffffff pc=0x80cdf14]

goroutine 1310 gp=0x8c077a8 m=90 mp=0x908e008 [running]:
runtime.throw({0x85897db, 0x5})
/opt/hostedtoolcache/go/1.23.4/x64/src/runtime/panic.go:1067 +0x35 fp=0x8cd3b80 sp=0x8cd3b6c pc=0x80c2d55
runtime.sigpanic()
/opt/hostedtoolcache/go/1.23.4/x64/src/runtime/signal_unix.go:931 +0x2af fp=0x8cd3bac sp=0x8cd3b80 pc=0x80c499f
internal/stringslite.Index({0x8c25740, 0x29}, {0xffffffff, 0x24})
/opt/hostedtoolcache/go/1.23.4/x64/src/internal/stringslite/strings.go:78 +0x54 fp=0x8cd3bf4 sp=0x8cd3bac pc=0x80cdf14
strings.Index(...)
/opt/hostedtoolcache/go/1.23.4/x64/src/strings/strings.go:1221
strings.Contains(...)
/opt/hostedtoolcache/go/1.23.4/x64/src/strings/strings.go:62
github.com/opencontainers/runc/libcontainer/integration.testUpdateDevices(0x8cd8808, 0x1)
/home/runner/work/runc/runc/libcontainer/integration/update_test.go:71 +0x8cf fp=0x8cd3f68 sp=0x8cd3bf4 pc=0x84bae5f
github.com/opencontainers/runc/libcontainer/integration.TestUpdateDevicesSystemd(0x8cd8808)
/home/runner/work/runc/runc/libcontainer/integration/update_test.go:97 +0x83 fp=0x8cd3f84 sp=0x8cd3f68 pc=0x84bb203
testing.tRunner(0x8cd8808, 0x85b26c0)
/opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:1690 +0x119 fp=0x8cd3fe4 sp=0x8cd3f84 pc=0x818fb29
testing.(*T).Run.gowrap1()
/opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:1743 +0x2e fp=0x8cd3ff0 sp=0x8cd3fe4 pc=0x8190b4e
runtime.goexit({})
/opt/hostedtoolcache/go/1.23.4/x64/src/runtime/asm_386.s:1393 +0x1 fp=0x8cd3ff4 sp=0x8cd3ff0 pc=0x80c9961
created by testing.(*T).Run in goroutine 1
/opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:1743 +0x3d1
...

FAIL github.com/opencontainers/runc/libcontainer/integration 18.695s

</details>

Both cases look like some kind of memory corruption.

### Steps to reproduce the issue

* Create a PR
* See ci / cross-i386 fails

### Describe the results you received and expected

no failures

### What version of runc are you using?

git HEAD

### Host OS information

_No response_

### Host kernel information

_No response_