From 330810d567fe361a5fd86febf54f79bb089e997e Mon Sep 17 00:00:00 2001
From: Michael Erickson <michae2@cockroachlabs.com>
Date: Fri, 22 Nov 2024 18:23:43 +0000
Subject: [PATCH] stats, encoding: improve UUID-decoding error
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Add a length check to `DecodeUUIDValue` and a more informative error
wrapping to `DecodeUpperBound`, which will hopefully help us track down
the cause of #128876.

The wrapped error message looks like:

```
decoding histogram version 3 type uuid value ‹666f6f›: invalid uuid length of 2
```

Informs: #128876

Epic: None

Release note: None
---
 pkg/sql/stats/histogram.go    | 7 +++++++
 pkg/util/encoding/encoding.go | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/pkg/sql/stats/histogram.go b/pkg/sql/stats/histogram.go
index 543ee70c24c0..ca87af77236d 100644
--- a/pkg/sql/stats/histogram.go
+++ b/pkg/sql/stats/histogram.go
@@ -7,6 +7,7 @@ package stats
 
 import (
 	"context"
+	"encoding/hex"
 	"fmt"
 	"math"
 	"sort"
@@ -114,6 +115,12 @@ func DecodeUpperBound(
 	} else {
 		datum, _, err = keyside.Decode(a, typ, upperBound, encoding.Ascending)
 	}
+	if err != nil {
+		err = errors.Wrapf(
+			err, "decoding histogram version %d type %v value %v",
+			int(version), typ.Family().Name(), hex.EncodeToString(upperBound),
+		)
+	}
 	return datum, err
 }
 
diff --git a/pkg/util/encoding/encoding.go b/pkg/util/encoding/encoding.go
index 862ec9041918..1e3357b96d76 100644
--- a/pkg/util/encoding/encoding.go
+++ b/pkg/util/encoding/encoding.go
@@ -3152,6 +3152,9 @@ func DecodeUUIDValue(b []byte) (remaining []byte, u uuid.UUID, err error) {
 
 // DecodeUntaggedUUIDValue decodes a value encoded by EncodeUntaggedUUIDValue.
 func DecodeUntaggedUUIDValue(b []byte) (remaining []byte, u uuid.UUID, err error) {
+	if len(b) < uuidValueEncodedLength {
+		return b, uuid.UUID{}, errors.Errorf("invalid uuid length of %d", len(b))
+	}
 	u, err = uuid.FromBytes(b[:uuidValueEncodedLength])
 	if err != nil {
 		return b, uuid.UUID{}, err