[PATCH] Fix Crypto digest.c kmapping sg entries > page in length

[Clay Haapala <chaapala@cisco.com>]

Below is the patch, against 2.6.7-rc2, to fix crypto/digest.c to do
multiple kmap()/kunmap() for scatterlist entries which have a size
greater than a single page, originally found and fixed by
N.C.Krishna Murthy <krmurthy@cisco.com>.
-- 
Clay Haapala (chaapala@cisco.com) Cisco Systems SRBU +1 763-398-1056
   6450 Wedgwood Rd, Suite 130 Maple Grove MN 55311 PGP: C89240AD
"We're serious about this campaign now!  The training wheels are coming off!"
   - a high White Horse Souse

Signed-off-by: Clay Haapala <chaapala@cisco.com>

diff -uNr --exclude=SCCS --exclude '*.mod.c' --exclude='*.o' --exclude='*.ko' --exclude '.*' linux-2.6.6-bk.orig/crypto/digest.c linux-2.6.6-bk/crypto/digest.c
--- linux-2.6.6-bk.orig/crypto/digest.c	2004-06-07 10:58:36.000000000 -0500
+++ linux-2.6.6-bk/crypto/digest.c	2004-06-07 15:21:05.000000000 -0500
@@ -27,13 +27,28 @@
                    struct scatterlist *sg, unsigned int nsg)
 {
 	unsigned int i;
-	
+
 	for (i = 0; i < nsg; i++) {
-		char *p = crypto_kmap(sg[i].page, 0) + sg[i].offset;
-		tfm->__crt_alg->cra_digest.dia_update(crypto_tfm_ctx(tfm),
-		                                      p, sg[i].length);
-		crypto_kunmap(p, 0);
-		crypto_yield(tfm);
+
+		struct page *pg = sg[i].page;
+		unsigned int offset = sg[i].offset;
+		unsigned int l = sg[i].length;
+
+		do {
+			unsigned int bytes_from_page = min(l, ((unsigned int)
+							   (PAGE_SIZE)) - 
+							   offset);
+			char *p = crypto_kmap(pg, 0) + offset;
+
+			tfm->__crt_alg->cra_digest.dia_update
+					(crypto_tfm_ctx(tfm), p,
+					 bytes_from_page);
+			crypto_kunmap(p, 0);
+			crypto_yield(tfm);
+			offset = 0;
+			pg++;
+			l -= bytes_from_page;
+		} while (l > 0);
 	}
 }