Messages in this thread Patch in this message | | | From | "Jason A. Donenfeld" <> | Subject | [PATCH v2 9/9] random: remove outdated INT_MAX >> 6 check in urandom_read() | Date | Wed, 9 Feb 2022 02:19:19 +0100 |
| |
In 79a8468747c5 ("random: check for increase of entropy_count because of signed conversion"), a number of checks were added around what values were passed to account(), because account() was doing fancy fixed point fractional arithmetic, and a user had some ability to pass large values directly into it. One of things in that commit was limiting those values to INT_MAX >> 6.
However, for several years now, urandom reads no longer touch entropy accounting, and so this check serves no purpose. The current flow is:
urandom_read_nowarn()-->get_random_bytes_user()-->chacha20_block()
We arrive at urandom_read_nowarn() in the first place either via ordinary fops, which limits reads to MAX_RW_COUNT, or via getrandom() which limits reads to INT_MAX.
Cc: Theodore Ts'o <tytso@mit.edu> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> --- drivers/char/random.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c index f7f9cbfe13f7..e09874c511d0 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1305,7 +1305,6 @@ static ssize_t urandom_read_nowarn(struct file *file, char __user *buf, { int ret; - nbytes = min_t(size_t, nbytes, INT_MAX >> 6); ret = get_random_bytes_user(buf, nbytes); trace_urandom_read(8 * nbytes, 0, input_pool.entropy_count); return ret; -- 2.35.0
| |