Fix max block size check
Since Go 1.1, `int` has been 64-bits on 64-bit platforms instead of
32-bits. This patch fixes the check to make sure the uncompressed
length is at most 2^32-1 bytes.
Fixes #15
diff --git a/decode.go b/decode.go
index a0d16e1..f3c9941 100644
--- a/decode.go
+++ b/decode.go
@@ -13,6 +13,8 @@
var (
// ErrCorrupt reports that the input is invalid.
ErrCorrupt = errors.New("snappy: corrupt input")
+ // ErrTooLarge reports that the uncompressed length is too large.
+ ErrTooLarge = errors.New("snappy: decoded block is too large")
// ErrUnsupported reports that the input isn't supported.
ErrUnsupported = errors.New("snappy: unsupported input")
)
@@ -27,11 +29,13 @@
// that the length header occupied.
func decodedLen(src []byte) (blockLen, headerLen int, err error) {
v, n := binary.Uvarint(src)
- if n <= 0 {
+ if n <= 0 || v > 0xffffffff {
return 0, 0, ErrCorrupt
}
- if uint64(int(v)) != v {
- return 0, 0, errors.New("snappy: decoded block is too large")
+
+ const wordSize = 32 << (^uint(0) >> 32 & 1)
+ if wordSize == 32 && v > 0x7fffffff {
+ return 0, 0, ErrTooLarge
}
return int(v), n, nil
}
diff --git a/snappy_test.go b/snappy_test.go
index d6a0397..f8188f1 100644
--- a/snappy_test.go
+++ b/snappy_test.go
@@ -86,6 +86,16 @@
if _, err := Decode(nil, data); err != ErrCorrupt {
t.Errorf("Decode: got %v, want ErrCorrupt", err)
}
+
+ // The encoded varint overflows 32 bits
+ data = []byte("\xff\xff\xff\xff\xff\x00")
+
+ if _, err := DecodedLen(data); err != ErrCorrupt {
+ t.Errorf("DecodedLen: got %v, want ErrCorrupt", err)
+ }
+ if _, err := Decode(nil, data); err != ErrCorrupt {
+ t.Errorf("Decode: got %v, want ErrCorrupt", err)
+ }
}
func cmp(a, b []byte) error {
