diff options
| author | Matt Mackall <mpm@selenic.com> | 2007-10-07 00:19:10 +0200 |
|---|---|---|
| committer | Adrian Bunk <bunk@kernel.org> | 2007-10-07 00:19:10 +0200 |
| commit | 5561123a8a3a55328174164901ef66f7a5ec2130 (patch) | |
| tree | d4e6f7fd90bf053b62c3ed0ddf8fb4e79b6abdbf /drivers/char/random.c | |
| parent | 9236d592ceee5d4033cd90d2f7d02440aea9b778 (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>
Diffstat (limited to 'drivers/char/random.c')
| -rw-r--r-- | drivers/char/random.c | 12 |
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); /* |