Messages in this thread | | | Date | Sun, 20 Feb 2022 19:56:21 -0800 | From | Eric Biggers <> | Subject | Re: [PATCH v2 9/9] random: remove outdated INT_MAX >> 6 check in urandom_read() |
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On Wed, Feb 09, 2022 at 02:19:19AM +0100, Jason A. Donenfeld wrote: > 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(-) >
Reviewed-by: Eric Biggers <ebiggers@google.com>
- Eric
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