Use SHL{8,32,64} in ed25519/ref10 to avoid left-shifting negative values

This helps us avoid undefined behavior. It's based on a patch from teor,
except that I wrote a perl script to regenerate the patch:

  #!/usr/bin/perl -p -w -i

  BEGIN { %vartypes = (); }

  if (/^[{}]/) {
      %vartypes = ();
  }

  if (/^ *crypto_int(\d+) +([a-zA-Z_][_a-zA-Z0-9]*)/) {
      $vartypes{$2} = $1;
  } elsif (/^ *(?:signed +)char +([a-zA-Z_][_a-zA-Z0-9]*)/) {
      $vartypes{$1} = '8';
  }

  # This fixes at most one shift per line. But that's all the code does.
  if (/([a-zA-Z_][a-zA-Z_0-9]*) *<< *(\d+)/) {
      $v = $1;
      if (exists $vartypes{$v}) {
  	s/$v *<< *(\d+)/SHL$vartypes{$v}($v,$1)/;
      }
  }

  # remove extra parenthesis
  s/\(SHL64\((.*)\)\)/SHL64\($1\)/;
  s/\(SHL32\((.*)\)\)/SHL32\($1\)/;
  s/\(SHL8\((.*)\)\)/SHL8\($1\)/;

1 files changed, 56 insertions, 56 deletions

diff --git a/src/ext/ed25519/ref10/sc_reduce.c b/src/ext/ed25519/ref10/sc_reduce.c
index d01f5a5737..c5afa53741 100644
--- a/src/ext/ed25519/ref10/sc_reduce.c
+++ b/src/ext/ed25519/ref10/sc_reduce.c
@@ -124,18 +124,18 @@ void sc_reduce(unsigned char *s)
   s11 -= s18 * 683901;
   s18 = 0;
 
-  carry6 = (s6 + (1<<20)) >> 21; s7 += carry6; s6 -= carry6 << 21;
-  carry8 = (s8 + (1<<20)) >> 21; s9 += carry8; s8 -= carry8 << 21;
-  carry10 = (s10 + (1<<20)) >> 21; s11 += carry10; s10 -= carry10 << 21;
-  carry12 = (s12 + (1<<20)) >> 21; s13 += carry12; s12 -= carry12 << 21;
-  carry14 = (s14 + (1<<20)) >> 21; s15 += carry14; s14 -= carry14 << 21;
-  carry16 = (s16 + (1<<20)) >> 21; s17 += carry16; s16 -= carry16 << 21;
+  carry6 = (s6 + (1<<20)) >> 21; s7 += carry6; s6 -= SHL64(carry6,21);
+  carry8 = (s8 + (1<<20)) >> 21; s9 += carry8; s8 -= SHL64(carry8,21);
+  carry10 = (s10 + (1<<20)) >> 21; s11 += carry10; s10 -= SHL64(carry10,21);
+  carry12 = (s12 + (1<<20)) >> 21; s13 += carry12; s12 -= SHL64(carry12,21);
+  carry14 = (s14 + (1<<20)) >> 21; s15 += carry14; s14 -= SHL64(carry14,21);
+  carry16 = (s16 + (1<<20)) >> 21; s17 += carry16; s16 -= SHL64(carry16,21);
 
-  carry7 = (s7 + (1<<20)) >> 21; s8 += carry7; s7 -= carry7 << 21;
-  carry9 = (s9 + (1<<20)) >> 21; s10 += carry9; s9 -= carry9 << 21;
-  carry11 = (s11 + (1<<20)) >> 21; s12 += carry11; s11 -= carry11 << 21;
-  carry13 = (s13 + (1<<20)) >> 21; s14 += carry13; s13 -= carry13 << 21;
-  carry15 = (s15 + (1<<20)) >> 21; s16 += carry15; s15 -= carry15 << 21;
+  carry7 = (s7 + (1<<20)) >> 21; s8 += carry7; s7 -= SHL64(carry7,21);
+  carry9 = (s9 + (1<<20)) >> 21; s10 += carry9; s9 -= SHL64(carry9,21);
+  carry11 = (s11 + (1<<20)) >> 21; s12 += carry11; s11 -= SHL64(carry11,21);
+  carry13 = (s13 + (1<<20)) >> 21; s14 += carry13; s13 -= SHL64(carry13,21);
+  carry15 = (s15 + (1<<20)) >> 21; s16 += carry15; s15 -= SHL64(carry15,21);
 
   s5 += s17 * 666643;
   s6 += s17 * 470296;
@@ -185,19 +185,19 @@ void sc_reduce(unsigned char *s)
   s5 -= s12 * 683901;
   s12 = 0;
 
-  carry0 = (s0 + (1<<20)) >> 21; s1 += carry0; s0 -= carry0 << 21;
-  carry2 = (s2 + (1<<20)) >> 21; s3 += carry2; s2 -= carry2 << 21;
-  carry4 = (s4 + (1<<20)) >> 21; s5 += carry4; s4 -= carry4 << 21;
-  carry6 = (s6 + (1<<20)) >> 21; s7 += carry6; s6 -= carry6 << 21;
-  carry8 = (s8 + (1<<20)) >> 21; s9 += carry8; s8 -= carry8 << 21;
-  carry10 = (s10 + (1<<20)) >> 21; s11 += carry10; s10 -= carry10 << 21;
+  carry0 = (s0 + (1<<20)) >> 21; s1 += carry0; s0 -= SHL64(carry0,21);
+  carry2 = (s2 + (1<<20)) >> 21; s3 += carry2; s2 -= SHL64(carry2,21);
+  carry4 = (s4 + (1<<20)) >> 21; s5 += carry4; s4 -= SHL64(carry4,21);
+  carry6 = (s6 + (1<<20)) >> 21; s7 += carry6; s6 -= SHL64(carry6,21);
+  carry8 = (s8 + (1<<20)) >> 21; s9 += carry8; s8 -= SHL64(carry8,21);
+  carry10 = (s10 + (1<<20)) >> 21; s11 += carry10; s10 -= SHL64(carry10,21);
 
-  carry1 = (s1 + (1<<20)) >> 21; s2 += carry1; s1 -= carry1 << 21;
-  carry3 = (s3 + (1<<20)) >> 21; s4 += carry3; s3 -= carry3 << 21;
-  carry5 = (s5 + (1<<20)) >> 21; s6 += carry5; s5 -= carry5 << 21;
-  carry7 = (s7 + (1<<20)) >> 21; s8 += carry7; s7 -= carry7 << 21;
-  carry9 = (s9 + (1<<20)) >> 21; s10 += carry9; s9 -= carry9 << 21;
-  carry11 = (s11 + (1<<20)) >> 21; s12 += carry11; s11 -= carry11 << 21;
+  carry1 = (s1 + (1<<20)) >> 21; s2 += carry1; s1 -= SHL64(carry1,21);
+  carry3 = (s3 + (1<<20)) >> 21; s4 += carry3; s3 -= SHL64(carry3,21);
+  carry5 = (s5 + (1<<20)) >> 21; s6 += carry5; s5 -= SHL64(carry5,21);
+  carry7 = (s7 + (1<<20)) >> 21; s8 += carry7; s7 -= SHL64(carry7,21);
+  carry9 = (s9 + (1<<20)) >> 21; s10 += carry9; s9 -= SHL64(carry9,21);
+  carry11 = (s11 + (1<<20)) >> 21; s12 += carry11; s11 -= SHL64(carry11,21);
 
   s0 += s12 * 666643;
   s1 += s12 * 470296;
@@ -207,18 +207,18 @@ void sc_reduce(unsigned char *s)
   s5 -= s12 * 683901;
   s12 = 0;
 
-  carry0 = s0 >> 21; s1 += carry0; s0 -= carry0 << 21;
-  carry1 = s1 >> 21; s2 += carry1; s1 -= carry1 << 21;
-  carry2 = s2 >> 21; s3 += carry2; s2 -= carry2 << 21;
-  carry3 = s3 >> 21; s4 += carry3; s3 -= carry3 << 21;
-  carry4 = s4 >> 21; s5 += carry4; s4 -= carry4 << 21;
-  carry5 = s5 >> 21; s6 += carry5; s5 -= carry5 << 21;
-  carry6 = s6 >> 21; s7 += carry6; s6 -= carry6 << 21;
-  carry7 = s7 >> 21; s8 += carry7; s7 -= carry7 << 21;
-  carry8 = s8 >> 21; s9 += carry8; s8 -= carry8 << 21;
-  carry9 = s9 >> 21; s10 += carry9; s9 -= carry9 << 21;
-  carry10 = s10 >> 21; s11 += carry10; s10 -= carry10 << 21;
-  carry11 = s11 >> 21; s12 += carry11; s11 -= carry11 << 21;
+  carry0 = s0 >> 21; s1 += carry0; s0 -= SHL64(carry0,21);
+  carry1 = s1 >> 21; s2 += carry1; s1 -= SHL64(carry1,21);
+  carry2 = s2 >> 21; s3 += carry2; s2 -= SHL64(carry2,21);
+  carry3 = s3 >> 21; s4 += carry3; s3 -= SHL64(carry3,21);
+  carry4 = s4 >> 21; s5 += carry4; s4 -= SHL64(carry4,21);
+  carry5 = s5 >> 21; s6 += carry5; s5 -= SHL64(carry5,21);
+  carry6 = s6 >> 21; s7 += carry6; s6 -= SHL64(carry6,21);
+  carry7 = s7 >> 21; s8 += carry7; s7 -= SHL64(carry7,21);
+  carry8 = s8 >> 21; s9 += carry8; s8 -= SHL64(carry8,21);
+  carry9 = s9 >> 21; s10 += carry9; s9 -= SHL64(carry9,21);
+  carry10 = s10 >> 21; s11 += carry10; s10 -= SHL64(carry10,21);
+  carry11 = s11 >> 21; s12 += carry11; s11 -= SHL64(carry11,21);
 
   s0 += s12 * 666643;
   s1 += s12 * 470296;
@@ -228,47 +228,47 @@ void sc_reduce(unsigned char *s)
   s5 -= s12 * 683901;
   s12 = 0;
 
-  carry0 = s0 >> 21; s1 += carry0; s0 -= carry0 << 21;
-  carry1 = s1 >> 21; s2 += carry1; s1 -= carry1 << 21;
-  carry2 = s2 >> 21; s3 += carry2; s2 -= carry2 << 21;
-  carry3 = s3 >> 21; s4 += carry3; s3 -= carry3 << 21;
-  carry4 = s4 >> 21; s5 += carry4; s4 -= carry4 << 21;
-  carry5 = s5 >> 21; s6 += carry5; s5 -= carry5 << 21;
-  carry6 = s6 >> 21; s7 += carry6; s6 -= carry6 << 21;
-  carry7 = s7 >> 21; s8 += carry7; s7 -= carry7 << 21;
-  carry8 = s8 >> 21; s9 += carry8; s8 -= carry8 << 21;
-  carry9 = s9 >> 21; s10 += carry9; s9 -= carry9 << 21;
-  carry10 = s10 >> 21; s11 += carry10; s10 -= carry10 << 21;
+  carry0 = s0 >> 21; s1 += carry0; s0 -= SHL64(carry0,21);
+  carry1 = s1 >> 21; s2 += carry1; s1 -= SHL64(carry1,21);
+  carry2 = s2 >> 21; s3 += carry2; s2 -= SHL64(carry2,21);
+  carry3 = s3 >> 21; s4 += carry3; s3 -= SHL64(carry3,21);
+  carry4 = s4 >> 21; s5 += carry4; s4 -= SHL64(carry4,21);
+  carry5 = s5 >> 21; s6 += carry5; s5 -= SHL64(carry5,21);
+  carry6 = s6 >> 21; s7 += carry6; s6 -= SHL64(carry6,21);
+  carry7 = s7 >> 21; s8 += carry7; s7 -= SHL64(carry7,21);
+  carry8 = s8 >> 21; s9 += carry8; s8 -= SHL64(carry8,21);
+  carry9 = s9 >> 21; s10 += carry9; s9 -= SHL64(carry9,21);
+  carry10 = s10 >> 21; s11 += carry10; s10 -= SHL64(carry10,21);
 
   s[0] = s0 >> 0;
   s[1] = s0 >> 8;
-  s[2] = (s0 >> 16) | (s1 << 5);
+  s[2] = (s0 >> 16) | SHL64(s1,5);
   s[3] = s1 >> 3;
   s[4] = s1 >> 11;
-  s[5] = (s1 >> 19) | (s2 << 2);
+  s[5] = (s1 >> 19) | SHL64(s2,2);
   s[6] = s2 >> 6;
-  s[7] = (s2 >> 14) | (s3 << 7);
+  s[7] = (s2 >> 14) | SHL64(s3,7);
   s[8] = s3 >> 1;
   s[9] = s3 >> 9;
-  s[10] = (s3 >> 17) | (s4 << 4);
+  s[10] = (s3 >> 17) | SHL64(s4,4);
   s[11] = s4 >> 4;
   s[12] = s4 >> 12;
-  s[13] = (s4 >> 20) | (s5 << 1);
+  s[13] = (s4 >> 20) | SHL64(s5,1);
   s[14] = s5 >> 7;
-  s[15] = (s5 >> 15) | (s6 << 6);
+  s[15] = (s5 >> 15) | SHL64(s6,6);
   s[16] = s6 >> 2;
   s[17] = s6 >> 10;
-  s[18] = (s6 >> 18) | (s7 << 3);
+  s[18] = (s6 >> 18) | SHL64(s7,3);
   s[19] = s7 >> 5;
   s[20] = s7 >> 13;
   s[21] = s8 >> 0;
   s[22] = s8 >> 8;
-  s[23] = (s8 >> 16) | (s9 << 5);
+  s[23] = (s8 >> 16) | SHL64(s9,5);
   s[24] = s9 >> 3;
   s[25] = s9 >> 11;
-  s[26] = (s9 >> 19) | (s10 << 2);
+  s[26] = (s9 >> 19) | SHL64(s10,2);
   s[27] = s10 >> 6;
-  s[28] = (s10 >> 14) | (s11 << 7);
+  s[28] = (s10 >> 14) | SHL64(s11,7);
   s[29] = s11 >> 1;
   s[30] = s11 >> 9;
   s[31] = s11 >> 17;