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From: Nicolai Stange <nicstange@gmail.com>
To: Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>
Cc: Tadeusz Struk <tadeusz.struk@intel.com>,
	Michal Marek <mmarek@suse.com>,
	Andrzej Zaborowski <andrew.zaborowski@intel.com>,
	Stephan Mueller <smueller@chronox.de>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
	Nicolai Stange <nicstange@gmail.com>
Subject: [PATCH v3 03/14] lib/mpi: mpi_write_sgl(): purge redundant pointer arithmetic
Date: Tue, 22 Mar 2016 13:12:37 +0100	[thread overview]
Message-ID: <1458648768-1469-4-git-send-email-nicstange@gmail.com> (raw)
In-Reply-To: <1458648768-1469-1-git-send-email-nicstange@gmail.com>

Within the copying loop in mpi_write_sgl(), we have

  if (lzeros) {
    ...
    p -= lzeros;
    y = lzeros;
  }
  p = p - (sizeof(alimb) - y);

If lzeros == 0, then y == 0, too. Thus, lzeros gets subtracted and added
back again to p.

Purge this redundancy.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
---
 lib/mpi/mpicoder.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index d8b372b..78ec4e1 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -407,12 +407,11 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
 			mpi_limb_t *limb2 = (void *)p - sizeof(alimb)
 				+ lzeros;
 			*limb1 = *limb2;
-			p -= lzeros;
 			y = lzeros;
 			lzeros = 0;
 		}
 
-		p = p - (sizeof(alimb) - y);
+		p = p - sizeof(alimb);
 
 		for (x = 0; x < sizeof(alimb) - y; x++) {
 			if (!buf_len) {
-- 
2.7.4

  parent reply	other threads:[~2016-03-22 12:12 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-22 12:12 [PATCH v3 00/14] lib/mpi: bug fixes and cleanup Nicolai Stange
2016-03-22 12:12 ` [PATCH v3 01/14] lib/mpi: mpi_write_sgl(): fix skipping of leading zero limbs Nicolai Stange
2016-03-22 12:12 ` [PATCH v3 02/14] lib/mpi: mpi_write_sgl(): fix style issue with lzero decrement Nicolai Stange
2016-03-22 12:12 ` Nicolai Stange [this message]
2016-03-22 12:12 ` [PATCH v3 04/14] lib/mpi: mpi_write_sgl(): fix out-of-bounds stack access Nicolai Stange
2016-03-22 12:12 ` [PATCH v3 05/14] lib/mpi: mpi_write_sgl(): replace open coded endian conversion Nicolai Stange
2016-03-22 12:12 ` [PATCH v3 06/14] lib/mpi: mpi_read_buffer(): optimize skipping of leading zero limbs Nicolai Stange
2016-03-22 12:12 ` [PATCH v3 07/14] lib/mpi: mpi_read_buffer(): replace open coded endian conversion Nicolai Stange
2016-03-22 12:12 ` [PATCH v3 08/14] lib/mpi: mpi_read_buffer(): fix buffer overflow Nicolai Stange
2016-03-22 12:12 ` [PATCH v3 09/14] lib/mpi: mpi_read_raw_from_sgl(): replace len argument by nbytes Nicolai Stange
2016-03-22 12:12 ` [PATCH v3 10/14] lib/mpi: mpi_read_raw_from_sgl(): don't include leading zero SGEs in nbytes Nicolai Stange
2016-03-22 12:12 ` [PATCH v3 11/14] lib/mpi: mpi_read_raw_from_sgl(): purge redundant clearing of nbits Nicolai Stange
2016-03-22 12:17 ` [PATCH v3 12/14] lib/mpi: mpi_read_raw_from_sgl(): fix nbits calculation Nicolai Stange
2016-03-22 12:18 ` [PATCH v3 13/14] lib/mpi: mpi_read_raw_from_sgl(): sanitize meaning of indices Nicolai Stange
2016-03-22 12:18 ` [PATCH v3 14/14] lib/mpi: mpi_read_raw_from_sgl(): fix out-of-bounds buffer access Nicolai Stange
2016-04-05 12:47 ` [PATCH v3 00/14] lib/mpi: bug fixes and cleanup Herbert Xu
2016-04-05 12:49   ` Nicolai Stange

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