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| author | Nicholas Nethercote <nnethercote@mozilla.com> | 2015-01-26 20:22:38 -0800 |
|---|---|---|
| committer | Nicholas Nethercote <nnethercote@mozilla.com> | 2015-01-26 20:22:38 -0800 |
| commit | 256ffe5e30e8401c4648c75834e88fbb55606968 (patch) | |
| tree | b8a68f0f2fa6645f61745935471ada0bebaefb09 | |
| parent | 2dd953845e31647310622d8ebde64a4f4774dbd9 (diff) | |
| download | nss-hg-256ffe5e30e8401c4648c75834e88fbb55606968.tar.gz | |
Bug 1096741 (part 1) - In mp_exptmod_safe_i(), instantiate |powersArray| lazily, r=rrelyea, r=kaie
| -rw-r--r-- | lib/freebl/mpi/mpmontg.c | 25 |
1 files changed, 13 insertions, 12 deletions
diff --git a/lib/freebl/mpi/mpmontg.c b/lib/freebl/mpi/mpmontg.c index 388e20c68..d619360aa 100644 --- a/lib/freebl/mpi/mpmontg.c +++ b/lib/freebl/mpi/mpmontg.c @@ -883,8 +883,8 @@ mp_err mp_exptmod_safe_i(const mp_int * montBase, int expOff; mp_int accum1, accum2, accum[WEAVE_WORD_SIZE]; mp_int tmp; - unsigned char *powersArray; - unsigned char *powers; + unsigned char *powersArray = NULL; + unsigned char *powers = NULL; MP_DIGITS(&accum1) = 0; MP_DIGITS(&accum2) = 0; @@ -894,15 +894,6 @@ mp_err mp_exptmod_safe_i(const mp_int * montBase, MP_DIGITS(&accum[3]) = 0; MP_DIGITS(&tmp) = 0; - powersArray = (unsigned char *)malloc(num_powers*(nLen*sizeof(mp_digit)+1)); - if (powersArray == NULL) { - res = MP_MEM; - goto CLEANUP; - } - - /* powers[i] = base ** (i); */ - powers = (unsigned char *)MP_ALIGN(powersArray,num_powers); - /* grab the first window value. This allows us to preload accumulator1 * and save a conversion, some squares and a multiple*/ MP_CHECKOK( mpl_get_bits(exponent, @@ -924,6 +915,13 @@ mp_err mp_exptmod_safe_i(const mp_int * montBase, MP_CHECKOK( mp_copy(montBase, &accum[1]) ); SQR(montBase, &accum[2]); MUL_NOWEAVE(montBase, &accum[2], &accum[3]); + powersArray = (unsigned char *)malloc(num_powers*(nLen*sizeof(mp_digit)+1)); + if (!powersArray) { + res = MP_MEM; + goto CLEANUP; + } + /* powers[i] = base ** (i); */ \ + powers = (unsigned char *)MP_ALIGN(powersArray,num_powers); \ MP_CHECKOK( mpi_to_weave(accum, powers, nLen, num_powers) ); if (first_window < 4) { MP_CHECKOK( mp_copy(&accum[first_window], &accum1) ); @@ -945,7 +943,10 @@ mp_err mp_exptmod_safe_i(const mp_int * montBase, * odd powers where k is the window size in the two other mp_modexpt * implementations in this file. We will get some of that * back by not needing the first 'k' squares and one multiply for the - * first window */ + * first window. + * Given the value of 4 for WEAVE_WORD_SIZE, this loop will only execute if + * num_powers > 2, in which case powers will have been allocated. + */ for (i = WEAVE_WORD_SIZE; i < num_powers; i++) { int acc_index = i & (WEAVE_WORD_SIZE-1); /* i % WEAVE_WORD_SIZE */ if ( i & 1 ) { |