fix: remove unsafe pkg usage from util.mempool (#15428)

pkg/util/mempool/pool.go

@@ -1,25 +1,20 @@
 package mempool
 
 import (
-	"errors"
 	"fmt"
 	"sync"
 	"time"
-	"unsafe"
 
 	"github.com/dustin/go-humanize"
 	"github.com/prometheus/client_golang/prometheus"
 )
 
 var (
-	errSlabExhausted = errors.New("slab exhausted")
-
-	reasonSizeExceeded  = "size-exceeded"
-	reasonSlabExhausted = "slab-exhausted"
+	reasonSizeExceeded = "size-exceeded"
 )
 
 type slab struct {
-	buffer      chan unsafe.Pointer
+	buffer      chan []byte
 	size, count int
 	once        sync.Once
 	metrics     *metrics
@@ -39,11 +34,10 @@ func newSlab(bufferSize, bufferCount int, m *metrics) *slab {
 }
 
 func (s *slab) init() {
-	s.buffer = make(chan unsafe.Pointer, s.count)
+	s.buffer = make(chan []byte, s.count)
 	for i := 0; i < s.count; i++ {
 		buf := make([]byte, 0, s.size)
-		ptr := unsafe.Pointer(unsafe.SliceData(buf)) //#nosec G103 -- Simple arena allocator implementation, does not appear to allow for any unsafe operations.
-		s.buffer <- ptr
+		s.buffer <- buf
 	}
 	s.metrics.availableBuffersPerSlab.WithLabelValues(s.name).Set(float64(s.count))
 }
@@ -54,8 +48,7 @@ func (s *slab) get(size int) ([]byte, error) {
 
 	waitStart := time.Now()
 	// wait for available buffer on channel
-	ptr := <-s.buffer
-	buf := unsafe.Slice((*byte)(ptr), s.size) //#nosec G103 -- Simple arena allocator implementation, does not appear to allow for any unsafe operations.
+	buf := <-s.buffer
 	s.metrics.waitDuration.WithLabelValues(s.name).Observe(time.Since(waitStart).Seconds())
 
 	return buf[:size], nil
@@ -67,9 +60,8 @@ func (s *slab) put(buf []byte) {
 		panic("slab is not initialized")
 	}
 
-	ptr := unsafe.Pointer(unsafe.SliceData(buf)) //#nosec G103 -- Simple arena allocator implementation, does not appear to allow for any unsafe operations.
 	// Note that memory is NOT zero'd on return, but since all allocations are of defined widths and we only ever then read a record of exactly that width into the allocation, it will always be overwritten before use and can't leak.
-	s.buffer <- ptr
+	s.buffer <- buf
 }
 
 // MemPool is an Allocator implementation that uses a fixed size memory pool