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| author | Katie Hockman <katie@golang.org> | 2019-10-14 16:42:21 -0400 |
|---|---|---|
| committer | Katie Hockman <katiehockman@google.com> | 2019-10-16 23:10:06 +0000 |
| commit | 4cabf6992e98f74a324e6f814a7cb35e41b05f25 (patch) | |
| tree | 6f05cedcc780a19749a7e262cd6b0c0264008a1b | |
| parent | b17fd8e49d24eb298c53de5cd0a8923f1e0270ba (diff) | |
| download | go-4cabf6992e98f74a324e6f814a7cb35e41b05f25.tar.gz go-4cabf6992e98f74a324e6f814a7cb35e41b05f25.zip | |
[release-branch.go1.13-security] crypto/dsa: prevent bad public keys from causing panic
dsa.Verify might currently use a nil s inverse in a
multiplication if the public key contains a non-prime Q,
causing a panic. Change this to check that the mod
inverse exists before using it.
Fixes CVE-2019-17596
Change-Id: I94d5f3cc38f1b5d52d38dcb1d253c71b7fd1cae7
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/572809
Reviewed-by: Filippo Valsorda <valsorda@google.com>
(cherry picked from commit 9119dfb0511326d4485b248b83d4fde19c95d0f7)
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/575233
| -rw-r--r-- | src/crypto/dsa/dsa.go | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/src/crypto/dsa/dsa.go b/src/crypto/dsa/dsa.go index 575314b1b4..2fc4f1f05b 100644 --- a/src/crypto/dsa/dsa.go +++ b/src/crypto/dsa/dsa.go @@ -279,6 +279,9 @@ func Verify(pub *PublicKey, hash []byte, r, s *big.Int) bool { } w := new(big.Int).ModInverse(s, pub.Q) + if w == nil { + return false + } n := pub.Q.BitLen() if n&7 != 0 { |