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author | Roland Shoemaker <roland@golang.org> | 2022-03-28 18:41:26 -0700 |
---|---|---|
committer | Michael Knyszek <mknyszek@google.com> | 2022-07-12 15:05:39 +0000 |
commit | 08c46ed43d80bbb67cb904944ea3417989be4af3 (patch) | |
tree | 2a4e911fcd01ed5c8eacdd6ee3f56ecb3789c01c | |
parent | c4c1993fd2a5b26fe45c09592af6d3388a3b2e08 (diff) | |
download | go-08c46ed43d80bbb67cb904944ea3417989be4af3.tar.gz go-08c46ed43d80bbb67cb904944ea3417989be4af3.zip |
encoding/xml: use iterative Skip, rather than recursive
Prevents exhausting the stack limit in _incredibly_ deeply nested
structures.
Fixes #53614
Fixes CVE-2022-28131
Change-Id: I47db4595ce10cecc29fbd06afce7b299868599e6
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1419912
Reviewed-by: Julie Qiu <julieqiu@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/417062
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
-rw-r--r-- | src/encoding/xml/read.go | 15 | ||||
-rw-r--r-- | src/encoding/xml/read_test.go | 17 |
2 files changed, 25 insertions, 7 deletions
diff --git a/src/encoding/xml/read.go b/src/encoding/xml/read.go index 01613065e3..a6fb665458 100644 --- a/src/encoding/xml/read.go +++ b/src/encoding/xml/read.go @@ -747,12 +747,12 @@ Loop: } // Skip reads tokens until it has consumed the end element -// matching the most recent start element already consumed. -// It recurs if it encounters a start element, so it can be used to -// skip nested structures. +// matching the most recent start element already consumed, +// skipping nested structures. // It returns nil if it finds an end element matching the start // element; otherwise it returns an error describing the problem. func (d *Decoder) Skip() error { + var depth int64 for { tok, err := d.Token() if err != nil { @@ -760,11 +760,12 @@ func (d *Decoder) Skip() error { } switch tok.(type) { case StartElement: - if err := d.Skip(); err != nil { - return err - } + depth++ case EndElement: - return nil + if depth == 0 { + return nil + } + depth-- } } } diff --git a/src/encoding/xml/read_test.go b/src/encoding/xml/read_test.go index 42059db3ae..58d1eddb61 100644 --- a/src/encoding/xml/read_test.go +++ b/src/encoding/xml/read_test.go @@ -9,6 +9,7 @@ import ( "errors" "io" "reflect" + "runtime" "strings" "testing" "time" @@ -1109,3 +1110,19 @@ func TestCVE202228131(t *testing.T) { t.Fatalf("Unmarshal unexpected error: got %q, want %q", err, errExeceededMaxUnmarshalDepth) } } + +func TestCVE202230633(t *testing.T) { + if runtime.GOARCH == "wasm" { + t.Skip("causes memory exhaustion on js/wasm") + } + defer func() { + p := recover() + if p != nil { + t.Fatal("Unmarshal panicked") + } + }() + var example struct { + Things []string + } + Unmarshal(bytes.Repeat([]byte("<a>"), 17_000_000), &example) +} |