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authorNicolai Stange <nicstange@gmail.com>2016-05-26 13:05:32 +0200
committerHerbert Xu <herbert@gondor.apana.org.au>2016-05-31 16:41:59 +0800
commiteef0df6a59537032ab6b708f30b28d9530f8760e (patch)
tree3028a30022c96d7443a389dc7eff94cef65f2bd0 /lib/mpi
parentdfd90510672f69206942546e8df4f63cfa91eae6 (diff)
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lib/mpi: mpi_read_raw_data(): fix nbits calculation
The number of bits, nbits, is calculated in mpi_read_raw_data() as follows: nbits = nbytes * 8; Afterwards, the number of leading zero bits of the first byte get subtracted: nbits -= count_leading_zeros(buffer[0]); 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: e1045992949 ("MPILIB: Provide a function to read raw data into an MPI") Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'lib/mpi')
-rw-r--r--lib/mpi/mpicoder.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index 37d6a4edb33c..eda34aba017e 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -50,7 +50,7 @@ MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes)
return NULL;
}
if (nbytes > 0)
- nbits -= count_leading_zeros(buffer[0]);
+ nbits -= count_leading_zeros(buffer[0]) - (BITS_PER_LONG - 8);
nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
val = mpi_alloc(nlimbs);