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| author | Denys Vlasenko | 2022-05-01 02:06:20 +0200 |
|---|---|---|
| committer | Denys Vlasenko | 2022-05-01 02:06:20 +0200 |
| commit | 74716580380d609165cc0be1ae37ee52d77243b2 (patch) | |
| tree | b8b04c6a9d992c7360af1511a7dde16c15af6553 | |
| parent | fb4546c7af3d1d2f11fb7851b56104f5580f328f (diff) | |
| download | busybox-74716580380d609165cc0be1ae37ee52d77243b2.zip busybox-74716580380d609165cc0be1ae37ee52d77243b2.tar.gz | |
seedrng: do not hash lengths, they are very predictable
function old new delta
seedrng_main 982 930 -52
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
| -rw-r--r-- | util-linux/seedrng.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/util-linux/seedrng.c b/util-linux/seedrng.c index 3074e9a..2965f3d 100644 --- a/util-linux/seedrng.c +++ b/util-linux/seedrng.c @@ -151,7 +151,8 @@ static void seed_from_file_if_exists(const char *filename, int dfd, bool credit, */ fsync(dfd); - sha256_hash(hash, &seed_len, sizeof(seed_len)); +//Length is not random, and taking its address spills variable to stack +// sha256_hash(hash, &seed_len, sizeof(seed_len)); sha256_hash(hash, seed, seed_len); printf("Seeding %u bits %s crediting\n", (unsigned)seed_len * 8, credit ? "and" : "without"); @@ -220,7 +221,8 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[]) new_seed_len = determine_optimal_seed_len(); new_seed_creditable = read_new_seed(new_seed, new_seed_len); - sha256_hash(&hash, &new_seed_len, sizeof(new_seed_len)); +//Length is not random, and taking its address spills variable to stack +// sha256_hash(&hash, &new_seed_len, sizeof(new_seed_len)); sha256_hash(&hash, new_seed, new_seed_len); sha256_end(&hash, new_seed + new_seed_len - SHA256_OUTSIZE); @@ -230,7 +232,7 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[]) xwrite(fd, new_seed, new_seed_len); if (new_seed_creditable) { /* More paranoia when we create a file which we believe contains - * genuine entropy: make sure disk is not full, quota was't esceeded, etc: + * genuine entropy: make sure disk is not full, quota was't exceeded, etc: */ if (fsync(fd) < 0) bb_perror_msg_and_die("can't write '%s'", NON_CREDITABLE_SEED_NAME); |