From: "Jason A. Donenfeld" Jason@zx2c4.com
commit 7b5164fb1279bf0251371848e40bae646b59b3a8 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/char/random.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
--- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1334,19 +1334,24 @@ static __poll_t random_poll(struct file 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,