svn commit: r278927 - head/sys/dev/random

[John-Mark Gurney]

Author: jmg
Date: Tue Feb 17 23:14:26 2015
New Revision: 278927
URL: https://svnweb.freebsd.org/changeset/base/278927

Log:
  Fix a bug where this function overflowed it's buffer...  This was
  causing ZFS panics on boot...
  
  This is purely reviewed and tested by peter.
  
  Reviewed by:	peter
  Approved by:	so (implicit), peter

Modified:
  head/sys/dev/random/yarrow.c

Modified: head/sys/dev/random/yarrow.c
==============================================================================
--- head/sys/dev/random/yarrow.c	Tue Feb 17 23:13:45 2015	(r278926)
+++ head/sys/dev/random/yarrow.c	Tue Feb 17 23:14:26 2015	(r278927)
@@ -432,6 +432,7 @@ reseed(u_int fastslow)
 void
 random_yarrow_read(uint8_t *buf, u_int bytecount)
 {
+	uint8_t tbuf[BLOCKSIZE];
 	u_int blockcount, i;
 
 	/* Check for initial/final read requests */
@@ -448,8 +449,15 @@ random_yarrow_read(uint8_t *buf, u_int b
 			yarrow_state.outputblocks = 0;
 		}
 		uint128_increment(&yarrow_state.counter.whole);
-		randomdev_encrypt(&yarrow_state.key, yarrow_state.counter.byte, buf, BLOCKSIZE);
-		buf += BLOCKSIZE;
+		if ((i + 1) * BLOCKSIZE > bytecount) {
+			randomdev_encrypt(&yarrow_state.key,
+			    yarrow_state.counter.byte, tbuf, BLOCKSIZE);
+			memcpy(buf, tbuf, bytecount - i * BLOCKSIZE);
+		} else {
+			randomdev_encrypt(&yarrow_state.key,
+			    yarrow_state.counter.byte, buf, BLOCKSIZE);
+			buf += BLOCKSIZE;
+		}
 	}
 
 	mtx_unlock(&random_reseed_mtx);