commit f227e3ec3b5cad859ad15666874405e8c1bbc1d4 upstream.
This modifies the first 32 bits out of the 128 bits of a random CPU's
net_rand_state on interrupt or CPU activity to complicate remote
observations that could lead to guessing the network RNG's internal
state.
Note that depending on some network devices' interrupt rate moderation
or binding, this re-seeding might happen on every packet or even almost
never.
In addition, with NOHZ some CPUs might not even get timer interrupts,
leaving their local state rarely updated, while they are running
networked processes making use of the random state. For this reason, we
also perform this update in update_process_times() in order to at least
update the state when there is user or system activity, since it's the
only case we care about.
Reported-by: Amit Klein <aksecurity@gmail.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e2a71bdea81690b6ef11f4368261ec6f5b6891aa upstream.
When an expiration delta falls into the last level of the wheel, that delta
has be compared against the maximum possible delay and reduced to fit in if
necessary.
However instead of comparing the delta against the maximum, the code
compares the actual expiry against the maximum. Then instead of fixing the
delta to fit in, it sets the maximum delta as the expiry value.
This can result in various undesired outcomes, the worst possible one
being a timer expiring 15 days ahead to fire immediately.
Fixes: 500462a9de65 ("timers: Switch to a non-cascading wheel")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200717140551.29076-2-frederic@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 30c66fc30ee7a98c4f3adf5fb7e213b61884474f upstream.
When a timer is enqueued with a negative delta (ie: expiry is below
base->clk), it gets added to the wheel as expiring now (base->clk).
Yet the value that gets stored in base->next_expiry, while calling
trigger_dyntick_cpu(), is the initial timer->expires value. The
resulting state becomes:
base->next_expiry < base->clk
On the next timer enqueue, forward_timer_base() may accidentally
rewind base->clk. As a possible outcome, timers may expire way too
early, the worst case being that the highest wheel levels get spuriously
processed again.
To prevent from that, make sure that base->next_expiry doesn't get below
base->clk.
Fixes: a683f390b93f ("timers: Forward the wheel clock whenever possible")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200703010657.2302-1-frederic@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Willy Tarreau