Harden cataloger parsers against truncated input (do not panic) (#5355)

* fix(javascript): don't panic on a yarn v1 lockfile line missing its value

A v1 `yarn.lock` dependency line without a version constraint, or a
`version`/`resolved`/`integrity` line without a value, indexed past the end of
the split line. Such dependencies are now skipped and empty fields left empty.

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* fix(alpine): don't panic on an apk db ACL or checksum line before its entry

An `M:`, `a:` or `Z:` line that comes before any directory or file entry in
`lib/apk/db/installed` indexed `files[-1]`. Such a line is now skipped.

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* fix(erlang): don't panic on a truncated rebar.lock or .app file

The term parser read past the end of the input when a file ended mid-term:
whitespace only, an unclosed list, a lone `<`, or a comment ending in `\r`.
These now return an "unexpected end of input" error.

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* fix(lua): don't panic on a truncated .rockspec

The rockspec parser read past the end of the input when a file ended mid-statement:
a lone `[`, an unclosed `[[...]]` value or `[...]` index, or a `local` assignment cut off
before its `=`, value, or line end. These now return an "unexpected end of input" error.

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* fix(swift): don't panic on a Podfile.lock pod without a version

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* fix(gentoo): don't panic on a short obj line in portage CONTENTS

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* fix(spdx): don't panic on an opam checksum without an algorithm

The opam cataloger stores checksums verbatim, so a malformed one reached the SPDX encoder and panicked there, outside the cataloger's recover. Checksums without an `=` are now skipped.

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* refactor: use strings.Cut where a split was only indexed after a Contains check

Also guards `windows.FromPosix` against a path with no separator.

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* test: guard untyped package metadata fields

- new `any`-typed metadata fields must be allowlisted with a reason
- allowlisted untyped fields are pushed through `SetID` and every encoder with
  non-finite, deeply nested and large values

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* test: fuzz every generic cataloger parser

One fuzz target over every glob-selected parser in the capabilities data, run
through its cataloger task. Each input must not panic, must finish in time and
must keep allocations proportional to its size. Seeds come from each parser's
testdata plus the string literals in its package.

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* test: scan malformed inputs under memory and time limits

A directory of small malformed files (deep nesting, oversized declared counts,
truncation, type mismatches, non-finite floats) is scanned by the CLI with a
memory limit and an RSS ceiling. The scan must exit 0 and write an SBOM.

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* test: stop a fuzz input once its live heap passes the allocation limit

The allocation check only ran after the parser returned, so an input on its way to exhausting memory ran the machine into swap first. The harness now polls the live heap while the parser runs and panics past the same limit, which the fuzz engine saves as a crasher.

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* fix: bound nesting depth and error context in the erlang and lua parsers

- a deeply nested rebar.lock or .rockspec overflowed the goroutine stack, which is fatal rather than a recoverable panic, so one file could take down the whole scan. Both parsers now stop at 1000 levels with an error.
- parse errors echoed whole input lines into the SBOM as unknowns, and lua appended another copy at every nesting level. `PrintError` now clips to a window around the error column, and lua decorates once at the top.
- the Podfile.lock error no longer echoes the pod entry.

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* test: close ways the malformed-input checks could pass quietly

- a ctx-aware parser hitting the fuzz timeout now fails the input instead of racing the hard deadline
- the heap watchdog measures growth from a post-GC baseline rather than an absolute process-wide number
- a saved fuzz input naming a target that no longer exists fails instead of being skipped
- the CLI malformed-input scan fails on a recovered parser panic, not only on a non-zero exit

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

---------

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

internal/packagemetadata/untyped_fields_test.go

@@ -0,0 +1,74 @@
+package packagemetadata
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+// untypedFieldAllowlist holds package metadata fields that are allowed to carry untyped (interface) values.
+// Values in these fields come straight from whatever a parser decoded, so they are not shaped by syft
+// and can hold anything an encoder or hasher chokes on. Every entry is part of existing SBOM output and
+// cannot be retyped without breaking it; new entries need a reason and a review.
+var untypedFieldAllowlist = map[string]string{
+	"GGUFFileHeader.RemainingKeyValues": "raw GGUF header key-values; retyping changes the header output and metadataHash",
+}
+
+// TestNoUntypedMetadataFields fails when a package metadata type gains a field typed any, []any,
+// map[string]any (or any other interface) that is not on the allowlist.
+func TestNoUntypedMetadataFields(t *testing.T) {
+	var hits []string
+	for _, ty := range AllTypes() {
+		rt := reflect.TypeOf(ty)
+		collectUntyped(rt, rt.Name(), map[reflect.Type]bool{}, &hits)
+	}
+
+	seen := map[string]bool{}
+	for _, h := range hits {
+		seen[h] = true
+		if _, ok := untypedFieldAllowlist[h]; !ok {
+			t.Errorf("untyped field %s: use a concrete type, or add it to untypedFieldAllowlist with a reason", h)
+		}
+	}
+	for k := range untypedFieldAllowlist {
+		if !seen[k] {
+			t.Errorf("stale untypedFieldAllowlist entry %s: field no longer exists or is now typed", k)
+		}
+	}
+}
+
+// collectUntyped records "Struct.Field" for every field whose type reaches an interface, descending
+// through pointers, slices, arrays, maps and nested syft-owned structs.
+func collectUntyped(rt reflect.Type, path string, visited map[reflect.Type]bool, hits *[]string) {
+	switch rt.Kind() {
+	case reflect.Interface:
+		*hits = append(*hits, path)
+	case reflect.Pointer, reflect.Slice, reflect.Array:
+		collectUntyped(rt.Elem(), path, visited, hits)
+	case reflect.Map:
+		collectUntyped(rt.Key(), path, visited, hits)
+		collectUntyped(rt.Elem(), path, visited, hits)
+	case reflect.Struct:
+		if visited[rt] {
+			return
+		}
+		if rt.Name() != "" && !strings.HasPrefix(rt.PkgPath(), "github.com/anchore/syft/") {
+			// a third-party type in the model carries whatever shape the library gives it (the same leak as an
+			// interface field), so it counts as untyped. The standard library is left alone.
+			if strings.Contains(strings.Split(rt.PkgPath(), "/")[0], ".") {
+				*hits = append(*hits, path)
+			}
+			return
+		}
+		visited[rt] = true
+		for i := 0; i < rt.NumField(); i++ {
+			f := rt.Field(i)
+			// unexported embedded structs still promote their exported fields to the encoders and the hasher. A
+			// field is only out of reach when it is neither encoded nor hashed by SetID.
+			if (!f.IsExported() && !f.Anonymous) || (f.Tag.Get("json") == "-" && f.Tag.Get("hash") == "ignore") {
+				continue
+			}
+			collectUntyped(f.Type, rt.Name()+"."+f.Name, visited, hits)
+		}
+	}
+}