linux/lib/mpi
Nicolai Stange 64c09b0b59 lib/mpi: mpi_read_raw_from_sgl(): fix nbits calculation
The number of bits, nbits, is calculated in mpi_read_raw_from_sgl() as
follows:

  nbits = nbytes * 8;

Afterwards, the number of leading zero bits of the first byte get
subtracted:

  nbits -= count_leading_zeros(*(u8 *)(sg_virt(sgl) + lzeros));

However, count_leading_zeros() takes an unsigned long and thus,
the u8 gets promoted to an unsigned long.

Thus, the above doesn't subtract the number of leading zeros in the most
significant nonzero input byte from nbits, but the number of leading
zeros of the most significant nonzero input byte promoted to unsigned long,
i.e. BITS_PER_LONG - 8 too many.

Fix this by subtracting

  count_leading_zeros(...) - (BITS_PER_LONG - 8)

from nbits only.

Fixes: 2d4d1eea54 ("lib/mpi: Add mpi sgl helpers")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2016-04-05 20:35:51 +08:00
..
generic_mpih-add1.c crypto: GnuPG based MPI lib - source files (part 1) 2011-11-09 11:45:22 +02:00
generic_mpih-lshift.c crypto: GnuPG based MPI lib - source files (part 1) 2011-11-09 11:45:22 +02:00
generic_mpih-mul1.c crypto: GnuPG based MPI lib - source files (part 1) 2011-11-09 11:45:22 +02:00
generic_mpih-mul2.c crypto: GnuPG based MPI lib - source files (part 1) 2011-11-09 11:45:22 +02:00
generic_mpih-mul3.c crypto: GnuPG based MPI lib - source files (part 1) 2011-11-09 11:45:22 +02:00
generic_mpih-rshift.c crypto: GnuPG based MPI lib - source files (part 1) 2011-11-09 11:45:22 +02:00
generic_mpih-sub1.c crypto: GnuPG based MPI lib - source files (part 1) 2011-11-09 11:45:22 +02:00
longlong.h lib/mpi: avoid assembler warning 2016-02-28 03:26:34 +08:00
Makefile MPILIB: Reinstate mpi_cmp[_ui]() and export for RSA signature verification 2012-10-08 13:50:15 +10:30
mpi-bit.c MPILIB: Provide count_leading/trailing_zeros() based on arch functions 2012-10-08 13:50:11 +10:30
mpi-cmp.c MPILIB: Fix comparison of negative MPIs 2015-01-14 16:10:12 +00:00
mpi-inline.h lib/mpi: use "static inline" instead of "extern inline" 2016-02-28 03:26:34 +08:00
mpi-internal.h lib/mpi: use "static inline" instead of "extern inline" 2016-02-28 03:26:34 +08:00
mpi-pow.c MPILIB: Provide count_leading/trailing_zeros() based on arch functions 2012-10-08 13:50:11 +10:30
mpicoder.c lib/mpi: mpi_read_raw_from_sgl(): fix nbits calculation 2016-04-05 20:35:51 +08:00
mpih-cmp.c crypto: GnuPG based MPI lib - source files (part 1) 2011-11-09 11:45:22 +02:00
mpih-div.c Remove unused code from MPI library 2012-05-26 11:51:03 +10:00
mpih-mul.c Remove unused code from MPI library 2012-05-26 11:51:03 +10:00
mpiutil.c MPILIB: add mpi_read_buf() and mpi_get_size() helpers 2015-06-16 14:35:06 +08:00