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authorMatt Mackall <mpm@selenic.com>2007-10-07 00:19:10 +0200
committerAdrian Bunk <bunk@kernel.org>2007-10-07 00:19:10 +0200
commit5561123a8a3a55328174164901ef66f7a5ec2130 (patch)
treed4e6f7fd90bf053b62c3ed0ddf8fb4e79b6abdbf
parent9236d592ceee5d4033cd90d2f7d02440aea9b778 (diff)
random: fix error in entropy extraction (CVE-2007-2453 1 of 2)
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: Adrian Bunk <bunk@kernel.org>
-rw-r--r--drivers/char/random.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 86be04b241e1..e237237b3c4a 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -758,7 +758,7 @@ 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);
@@ -770,9 +770,11 @@ 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);
}
/*
@@ -780,7 +782,7 @@ 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);
/*