error read auxv in vdsoMemoryAddress function in arm_32 env

[hailwind]

Describe the bug
EOF read auxv in vdsoMemoryAddress function in arm_32 env

code position
https://github.com/cilium/ebpf/blob/main/internal/vdso.go#L65

To Reproduce

#uint64
root@1c40e8105b98:/sdwan# ./testx 
2023/09/14 22:31:41 Tag: 13752409965245497377, Val: 17927356702261264
2023/09/14 22:31:41 Tag: 17592186044422, Val: 429496729617
2023/09/14 22:31:41 Tag: 281698315010051, Val: 137438953476
2023/09/14 22:31:41 Tag: 30064771077, Val: 7
2023/09/14 22:31:41 Tag: 8, Val: 286371239428105
2023/09/14 22:31:41 Tag: 11, Val: 12
2023/09/14 22:31:41 Tag: 13, Val: 14
2023/09/14 22:31:41 Tag: 23, Val: 13747605919770869785
2023/09/14 22:31:41 Tag: 26, Val: 13747607246915764255
2023/09/14 22:31:41 Tag: 13747605988490346511, Val: 0
2023/09/14 22:31:41 reading auxv entry: EOF

#uint32
root@1c40e8105b98:/tmp# ./testx 
2023/09/14 22:32:26 Tag: 33, Val: 3204325376
2023/09/14 22:32:26 aux.VAL: 3204325376

root@1c40e8105b98:/tmp# uname -a
Linux testx 5.15.130 #0 SMP Thu Sep 14 07:12:57 2023 armv7l GNU/Linux

troubleshooting code

package main

import (
	"encoding/binary"
	"errors"
	"log"
	"os"

	"golang.org/x/sys/unix"
)

func main() {
	av, err := os.Open("/proc/self/auxv")
	if errors.Is(err, unix.EACCES) {
		log.Printf("opening auxv: %s (process may not be dumpable due to file capabilities)", err)
	}

	if err != nil {
		log.Printf("opening auxv: %s", err)
	}
	defer av.Close()

	const (
		_AT_NULL         = 0  // End of vector
		_AT_SYSINFO_EHDR = 33 // Offset to vDSO blob in process image
	)
	var NativeEndian binary.ByteOrder = binary.LittleEndian
	// Loop through all tag/value pairs in auxv until we find `AT_SYSINFO_EHDR`,
	// the address of a page containing the virtual Dynamic Shared Object (vDSO).
	// aux := struct{ Tag, Val uint64 }{}
	aux := struct{ Tag, Val uint32 }{}
	for {
		if err := binary.Read(av, NativeEndian, &aux); err != nil {
			log.Printf("reading auxv entry: %s", err)
			break
		}
		log.Printf("Tag: %d, Val: %d", aux.Tag, aux.Val)
		switch aux.Tag {
		case _AT_SYSINFO_EHDR:

			if aux.Val != 0 {
				log.Printf("aux.VAL: %d", aux.Val)
				return
			} else {
				log.Printf(("invalid vDSO address in auxv"))
			}
		// _AT_NULL is always the last tag/val pair in the aux vector
		// and can be treated like EOF.
		case _AT_NULL:
			log.Printf("_AT_NULL")
		}
	}
}

compile:
GOOS=linux GOARCH=arm GOARM=7 CGO_ENABLED=1 CC=arm-linux-gnueabi-gcc go build -a -ldflags "-linkmode external -extldflags '-static' -s -w" -o testx main.go

Expected behavior
fix it in arm32

[lmb]

Thanks for the detailed bug report! We don't officially support arm32, so this is kind of expected. I'm happy to merge any fixes you come up with ofc.