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author | Katie Hockman <katie@golang.org> | 2020-01-24 15:29:12 -0500 |
---|---|---|
committer | Katie Hockman <katiehockman@google.com> | 2020-01-27 20:31:21 +0000 |
commit | 44bb3b4b5341f5bb373acb0b8130795f888c9ace (patch) | |
tree | 791443aa8c1cf962c1449a72322b812c15acd7b0 | |
parent | a8b372fb365f4b69f0b06aa9c3e642e6aa022840 (diff) | |
download | go-44bb3b4b5341f5bb373acb0b8130795f888c9ace.tar.gz go-44bb3b4b5341f5bb373acb0b8130795f888c9ace.zip |
[release-branch.go1.12-security] internal/x/crypto/cryptobyte: import security fix for 32-bit archs
cryptobyte: fix panic due to malformed ASN.1 inputs on 32-bit archs
When int is 32 bits wide (on 32-bit architectures like 386 and arm), an
overflow could occur, causing a panic, due to malformed ASN.1 being
passed to any of the ASN1 methods of String.
Tested on linux/386 and darwin/amd64.
This fixes CVE-2020-7919 and was found thanks to the Project Wycheproof
test vectors.
Change-Id: I8c9696a8bfad1b40ec877cd740dba3467d66ab54
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/645211
Reviewed-by: Katie Hockman <katiehockman@google.com>
Reviewed-by: Adam Langley <agl@google.com>
x/crypto/cryptobyte is used in crypto/x509 for parsing certificates.
Malformed certificates might cause a panic during parsing on 32-bit
architectures (like arm and 386).
Change-Id: I3c619af508bacff84023be4d5a7c4992c2f20a56
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/647483
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
-rw-r--r-- | src/internal/x/crypto/cryptobyte/asn1.go | 5 | ||||
-rw-r--r-- | src/internal/x/crypto/cryptobyte/asn1_test.go | 4 | ||||
-rw-r--r-- | src/internal/x/crypto/cryptobyte/string.go | 7 |
3 files changed, 8 insertions, 8 deletions
diff --git a/src/internal/x/crypto/cryptobyte/asn1.go b/src/internal/x/crypto/cryptobyte/asn1.go index 2d40680ddd..758ac3a649 100644 --- a/src/internal/x/crypto/cryptobyte/asn1.go +++ b/src/internal/x/crypto/cryptobyte/asn1.go @@ -470,7 +470,8 @@ func (s *String) ReadASN1GeneralizedTime(out *time.Time) bool { // It reports whether the read was successful. func (s *String) ReadASN1BitString(out *encoding_asn1.BitString) bool { var bytes String - if !s.ReadASN1(&bytes, asn1.BIT_STRING) || len(bytes) == 0 { + if !s.ReadASN1(&bytes, asn1.BIT_STRING) || len(bytes) == 0 || + len(bytes)*8/8 != len(bytes) { return false } @@ -740,7 +741,7 @@ func (s *String) readASN1(out *String, outTag *asn1.Tag, skipHeader bool) bool { length = headerLen + len32 } - if uint32(int(length)) != length || !s.ReadBytes((*[]byte)(out), int(length)) { + if int(length) < 0 || !s.ReadBytes((*[]byte)(out), int(length)) { return false } if skipHeader && !out.Skip(int(headerLen)) { diff --git a/src/internal/x/crypto/cryptobyte/asn1_test.go b/src/internal/x/crypto/cryptobyte/asn1_test.go index ca28e3bcfb..f90d768edb 100644 --- a/src/internal/x/crypto/cryptobyte/asn1_test.go +++ b/src/internal/x/crypto/cryptobyte/asn1_test.go @@ -31,6 +31,10 @@ var readASN1TestData = []readASN1Test{ {"non-minimal length", append([]byte{0x30, 0x82, 0, 0x80}, make([]byte, 0x80)...), 0x30, false, nil}, {"invalid tag", []byte{0xa1, 3, 0x4, 1, 1}, 31, false, nil}, {"high tag", []byte{0x1f, 0x81, 0x80, 0x01, 2, 1, 2}, 0xff /* actually 0x4001, but tag is uint8 */, false, nil}, + {"2**31 - 1 length", []byte{0x30, 0x84, 0x7f, 0xff, 0xff, 0xff}, 0x30, false, nil}, + {"2**32 - 1 length", []byte{0x30, 0x84, 0xff, 0xff, 0xff, 0xff}, 0x30, false, nil}, + {"2**63 - 1 length", []byte{0x30, 0x88, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}, 0x30, false, nil}, + {"2**64 - 1 length", []byte{0x30, 0x88, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}, 0x30, false, nil}, } func TestReadASN1(t *testing.T) { diff --git a/src/internal/x/crypto/cryptobyte/string.go b/src/internal/x/crypto/cryptobyte/string.go index bd2ed2e207..a3ecf63828 100644 --- a/src/internal/x/crypto/cryptobyte/string.go +++ b/src/internal/x/crypto/cryptobyte/string.go @@ -24,7 +24,7 @@ type String []byte // read advances a String by n bytes and returns them. If less than n bytes // remain, it returns nil. func (s *String) read(n int) []byte { - if len(*s) < n { + if len(*s) < n || n < 0 { return nil } v := (*s)[:n] @@ -105,11 +105,6 @@ func (s *String) readLengthPrefixed(lenLen int, outChild *String) bool { length = length << 8 length = length | uint32(b) } - if int(length) < 0 { - // This currently cannot overflow because we read uint24 at most, but check - // anyway in case that changes in the future. - return false - } v := s.read(int(length)) if v == nil { return false |