Fix bug in md5 calculation

Commit 8c432325c3df2075a77b27eab8a87704cf7b48ee introduced a bug for
smaller sizes. Just basically revert the optimization, safer to stay
with a 'reference' implementation than skip a memset.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/md5.c b/md5.c
index 6b61012e85da005d418a7c4ea1ef22349038ed82..cf1f814a0d63c2cee558c8049140156e90f9723c 100644 (file)
--- a/md5.c
+++ b/md5.c
@@ -9,11 +9,10 @@ static void md5_transform(uint32_t *hash, uint32_t const *in)
 {
        uint32_t a, b, c, d;
 
-       /*
-        * This used to be set from the hash[0..3] input, but we can
-        * skip a memory clear if we just start from 0 instead.
-        */
-       a = b = c = d = 0;
+       a = hash[0];
+       b = hash[1];
+       c = hash[2];
+       d = hash[3];
 
        MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
        MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
@@ -83,10 +82,10 @@ static void md5_transform(uint32_t *hash, uint32_t const *in)
        MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
        MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
 
-       hash[0] = a;
-       hash[1] = b;
-       hash[2] = c;
-       hash[3] = d;
+       hash[0] += a;
+       hash[1] += b;
+       hash[2] += c;
+       hash[3] += d;
 }
 
 void md5_update(struct md5_ctx *mctx, const uint8_t *data, unsigned int len)

diff --git a/verify.c b/verify.c
index 91509e5b7819426c1576fb8f81896c2de1b1a896..6972fe3ff59a2a10604ba708c05c2524a562c83f 100644 (file)
--- a/verify.c
+++ b/verify.c
@@ -145,6 +145,7 @@ static int verify_io_u_md5(struct verify_header *hdr, struct io_u *io_u,
                .hash = hash,
        };
 
+       memset(md5_ctx.hash, 0, sizeof(hdr->md5_digest));
        md5_update(&md5_ctx, p, hdr->len - sizeof(*hdr));
 
        if (memcmp(hdr->md5_digest, md5_ctx.hash, sizeof(hash))) {
@@ -236,6 +237,7 @@ static void fill_md5(struct verify_header *hdr, void *p, unsigned int len)
                .hash = (uint32_t *) hdr->md5_digest,
        };
 
+       memset(md5_ctx.hash, 0, sizeof(hdr->md5_digest));
        md5_update(&md5_ctx, p, len);
 }