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git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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>
authored by Matt Mackall and committed by Linus Torvalds 602b6aee f717221b
+7
-5
drivers/char/random.c
+7
-5
drivers/char/random.c
···
760
761
static void extract_buf(struct entropy_store *r, __u8 *out)
762
{
763
-
int i, x;
764
__u32 data[16], buf[5 + SHA_WORKSPACE_WORDS];
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sha_init(buf);
···
772
* attempts to find previous ouputs), unless the hash
773
* function can be inverted.
774
*/
775
-
for (i = 0, x = 0; i < r->poolinfo->poolwords; i += 16, x+=2) {
776
-
sha_transform(buf, (__u8 *)r->pool+i, buf + 5);
777
-
add_entropy_words(r, &buf[x % 5], 1);
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}
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/*
···
784
* portion of the pool while mixing, and hash one
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* final time.
786
*/
787
-
__add_entropy_words(r, &buf[x % 5], 1, data);
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sha_transform(buf, (__u8 *)data, buf + 5);
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/*
···
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761
static void extract_buf(struct entropy_store *r, __u8 *out)
762
{
763
+
int i;
764
__u32 data[16], buf[5 + SHA_WORKSPACE_WORDS];
765
766
sha_init(buf);
···
772
* attempts to find previous ouputs), unless the hash
773
* function can be inverted.
774
*/
775
+
for (i = 0; i < r->poolinfo->poolwords; i += 16) {
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+
/* hash blocks of 16 words = 512 bits */
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+
sha_transform(buf, (__u8 *)(r->pool + i), buf + 5);
778
+
/* feed back portion of the resulting hash */
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+
add_entropy_words(r, &buf[i % 5], 1);
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}
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/*
···
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* portion of the pool while mixing, and hash one
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* final time.
784
*/
785
+
__add_entropy_words(r, &buf[i % 5], 1, data);
786
sha_transform(buf, (__u8 *)data, buf + 5);
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/*