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commit 602b6aeefe8932dd8bb15014e8fe6bb25d736361
Author: Matt Mackall <mpm@selenic.com>
Date: Tue May 29 21:54:27 2007 -0500
random: fix error in entropy extraction
Fix cast error in entropy extraction.
Add comments explaining the magic 16.
Remove extra confusing loop variable.
Signed-off-by: Matt Mackall <mpm@selenic.com>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 46c1b97..9705b43 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -760,7 +760,7 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
static void extract_buf(struct entropy_store *r, __u8 *out)
{
- int i, x;
+ int i;
__u32 data[16], buf[5 + SHA_WORKSPACE_WORDS];
sha_init(buf);
@@ -772,9 +772,11 @@ static void extract_buf(struct entropy_store *r, __u8 *out)
* attempts to find previous ouputs), unless the hash
* function can be inverted.
*/
- for (i = 0, x = 0; i < r->poolinfo->poolwords; i += 16, x+=2) {
- sha_transform(buf, (__u8 *)r->pool+i, buf + 5);
- add_entropy_words(r, &buf[x % 5], 1);
+ for (i = 0; i < r->poolinfo->poolwords; i += 16) {
+ /* hash blocks of 16 words = 512 bits */
+ sha_transform(buf, (__u8 *)(r->pool + i), buf + 5);
+ /* feed back portion of the resulting hash */
+ add_entropy_words(r, &buf[i % 5], 1);
}
/*
@@ -782,7 +784,7 @@ static void extract_buf(struct entropy_store *r, __u8 *out)
* portion of the pool while mixing, and hash one
* final time.
*/
- __add_entropy_words(r, &buf[x % 5], 1, data);
+ __add_entropy_words(r, &buf[i % 5], 1, data);
sha_transform(buf, (__u8 *)data, buf + 5);
/*
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