From c8dba5dcb52c1957abcd4c6011d8a66498710f56 Mon Sep 17 00:00:00 2001
From: Catherine <whitequark@whitequark.org>
Date: Sat, 30 May 2026 14:04:10 +0000
Subject: [PATCH] Fix opaque panic when ingesting an invalid tar file.

Use PUT to upload the following tar file (`unzstd | base64 -d`):

KLUv/QRY7QIAcoQOFLCnDQ0QaaURkYASyN1LJveuZAKkXivfoQMXZ5MhIGJAXHUWHclJufKB
PLvNDSbmD81Htf9W1f/3BgsA/QPwwAuojAHiDA8mpAEqhsJB8IUcTATEusLVn0AbU7ZnkA==

After this commit it should no longer crash the handler.

V12-Ref: F-77219
---
 src/extract.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/extract.go b/src/extract.go
index 2cf20d6..333d6d4 100644
--- a/src/extract.go
+++ b/src/extract.go
@@ -124,10 +124,10 @@ func ExtractTar(ctx context.Context, reader io.Reader, oldManifest *Manifest) (*
 				dataBytesTransferred += int64(len(header.Linkname)) // actual symlink
 			}
 		case tar.TypeLink:
-			if entry, found := hardLinks[header.Linkname]; found {
+			if entry, found := hardLinks[header.Linkname]; found && entry != nil {
 				manifest.Contents[fileName] = entry
 			} else {
-				AddProblem(manifest, fileName, "tar: invalid hardlink %q", header.Linkname)
+				AddProblem(manifest, fileName, "tar: invalid hardlink to %q", header.Linkname)
 			}
 		case tar.TypeDir:
 			AddDirectory(manifest, fileName)