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| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-02-09 20:42:13 +0300 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-02-21 23:14:00 +0300 |
| commit | 7b5164fb1279bf0251371848e40bae646b59b3a8 (patch) | |
| tree | b733a6458feeaa478acc849f5d238c397accaaa5 | |
| parent | 434537ae54ad37e93555de21b6ac8133d6d773a9 (diff) | |
| download | linux-7b5164fb1279bf0251371848e40bae646b59b3a8.tar.xz | |
random: zero buffer after reading entropy from userspace
This buffer may contain entropic data that shouldn't stick around longer
than needed, so zero out the temporary buffer at the end of write_pool().
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
| -rw-r--r-- | drivers/char/random.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 896ec54f8f5c..8ae7d0b30280 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1336,19 +1336,24 @@ static __poll_t random_poll(struct file *file, poll_table *wait) static int write_pool(const char __user *ubuf, size_t count) { size_t len; + int ret = 0; u8 block[BLAKE2S_BLOCK_SIZE]; while (count) { len = min(count, sizeof(block)); - if (copy_from_user(block, ubuf, len)) - return -EFAULT; + if (copy_from_user(block, ubuf, len)) { + ret = -EFAULT; + goto out; + } count -= len; ubuf += len; mix_pool_bytes(block, len); cond_resched(); } - return 0; +out: + memzero_explicit(block, sizeof(block)); + return ret; } static ssize_t random_write(struct file *file, const char __user *buffer, |