From 38d600147331d36e74174ebbd4008b63188b321b Mon Sep 17 00:00:00 2001 From: Andy Polyakov Date: Thu, 17 Aug 2017 21:08:57 +0200 Subject: [PATCH] bn/asm/x86_64-mont5.pl: fix carry bug in bn_sqrx8x_internal. Credit to OSS-Fuzz for finding this. CVE-2017-3736 Reviewed-by: Rich Salz --- crypto/bn/asm/x86_64-mont5.pl | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/crypto/bn/asm/x86_64-mont5.pl b/crypto/bn/asm/x86_64-mont5.pl index 3bb0cdf..42178e4 100755 --- a/crypto/bn/asm/x86_64-mont5.pl +++ b/crypto/bn/asm/x86_64-mont5.pl @@ -3090,11 +3090,19 @@ $code.=<<___; .align 32 .Lsqrx8x_break: - sub 16+8(%rsp),%r8 # consume last carry + xor $zero,$zero + sub 16+8(%rsp),%rbx # mov 16(%rsp),%cf + adcx $zero,%r8 mov 24+8(%rsp),$carry # initial $tptr, borrow $carry + adcx $zero,%r9 mov 0*8($aptr),%rdx # a[8], modulo-scheduled - xor %ebp,%ebp # xor $zero,$zero + adc \$0,%r10 mov %r8,0*8($tptr) + adc \$0,%r11 + adc \$0,%r12 + adc \$0,%r13 + adc \$0,%r14 + adc \$0,%r15 cmp $carry,$tptr # cf=0, of=0 je .Lsqrx8x_outer_loop -- 2.9.5