diff options
author | Andy Polyakov <appro@openssl.org> | 2015-12-01 09:00:32 +0100 |
---|---|---|
committer | Matt Caswell <matt@openssl.org> | 2015-12-03 13:12:01 +0000 |
commit | 29851264f11ccc70c6c0140d7e3d8d93ef5c9b11 (patch) | |
tree | 55e5ad3e76c2a869b25ef0f0ad438262f633e6ff | |
parent | b5516cfbd65de9331d827012fc5bdace1953613e (diff) | |
download | openssl-29851264f11ccc70c6c0140d7e3d8d93ef5c9b11.tar.gz |
bn/asm/x86_64-mont5.pl: fix carry propagating bug (CVE-2015-3193).
Reviewed-by: Richard Levitte <levitte@openssl.org>
-rwxr-xr-x | crypto/bn/asm/x86_64-mont5.pl | 22 | ||||
-rw-r--r-- | test/bntest.c | 18 |
2 files changed, 37 insertions, 3 deletions
diff --git a/crypto/bn/asm/x86_64-mont5.pl b/crypto/bn/asm/x86_64-mont5.pl index 388e3c6911..64e668f140 100755 --- a/crypto/bn/asm/x86_64-mont5.pl +++ b/crypto/bn/asm/x86_64-mont5.pl @@ -1784,6 +1784,15 @@ sqr8x_reduction: .align 32 .L8x_tail_done: add (%rdx),%r8 # can this overflow? + adc \$0,%r9 + adc \$0,%r10 + adc \$0,%r11 + adc \$0,%r12 + adc \$0,%r13 + adc \$0,%r14 + adc \$0,%r15 # can't overflow, because we + # started with "overhung" part + # of multiplication xor %rax,%rax neg $carry @@ -3130,6 +3139,15 @@ sqrx8x_reduction: .align 32 .Lsqrx8x_tail_done: add 24+8(%rsp),%r8 # can this overflow? + adc \$0,%r9 + adc \$0,%r10 + adc \$0,%r11 + adc \$0,%r12 + adc \$0,%r13 + adc \$0,%r14 + adc \$0,%r15 # can't overflow, because we + # started with "overhung" part + # of multiplication mov $carry,%rax # xor %rax,%rax sub 16+8(%rsp),$carry # mov 16(%rsp),%cf @@ -3173,13 +3191,11 @@ my ($rptr,$nptr)=("%rdx","%rbp"); my @ri=map("%r$_",(10..13)); my @ni=map("%r$_",(14..15)); $code.=<<___; - xor %rbx,%rbx + xor %ebx,%ebx sub %r15,%rsi # compare top-most words adc %rbx,%rbx mov %rcx,%r10 # -$num - .byte 0x67 or %rbx,%rax - .byte 0x67 mov %rcx,%r9 # -$num xor \$1,%rax sar \$3+2,%rcx # cf=0 diff --git a/test/bntest.c b/test/bntest.c index 9caa2c904b..9542800444 100644 --- a/test/bntest.c +++ b/test/bntest.c @@ -1023,6 +1023,24 @@ int test_mod_exp(BIO *bp, BN_CTX *ctx) return 0; } } + + /* Regression test for carry propagation bug in sqr8x_reduction */ + BN_hex2bn(&a, "050505050505"); + BN_hex2bn(&b, "02"); + BN_hex2bn(&c, + "4141414141414141414141274141414141414141414141414141414141414141" + "4141414141414141414141414141414141414141414141414141414141414141" + "4141414141414141414141800000000000000000000000000000000000000000" + "0000000000000000000000000000000000000000000000000000000000000000" + "0000000000000000000000000000000000000000000000000000000000000000" + "0000000000000000000000000000000000000000000000000000000001"); + BN_mod_exp(d, a, b, c, ctx); + BN_mul(e, a, a, ctx); + if (BN_cmp(d, e)) { + fprintf(stderr, "BN_mod_exp and BN_mul produce different results!\n"); + return 0; + } + BN_free(a); BN_free(b); BN_free(c); |