linux/drivers/net/wireguard
Linus Torvalds 8ca09d5fa3 cpumask: fix incorrect cpumask scanning result checks
It turns out that commit 596ff4a09b ("cpumask: re-introduce
constant-sized cpumask optimizations") exposed a number of cases of
drivers not checking the result of "cpumask_next()" and friends
correctly.

The documented correct check for "no more cpus in the cpumask" is to
check for the result being equal or larger than the number of possible
CPU ids, exactly _because_ we've always done those constant-sized
cpumask scans using a widened type before.  So the return value of a
cpumask scan should be checked with

	if (cpu >= nr_cpu_ids)
		...

because the cpumask scan did not necessarily stop exactly *at* that
maximum CPU id.

But a few cases ended up instead using checks like

	if (cpu == nr_cpumask_bits)
		...

which used that internal "widened" number of bits.  And that used to
work pretty much by accident (ok, in this case "by accident" is simply
because it matched the historical internal implementation of the cpumask
scanning, so it was more of a "intentionally using implementation
details rather than an accident").

But the extended constant-sized optimizations then did that internal
implementation differently, and now that code that did things wrong but
matched the old implementation no longer worked at all.

Which then causes subsequent odd problems due to using what ends up
being an invalid CPU ID.

Most of these cases require either unusual hardware or special uses to
hit, but the random.c one triggers quite easily.

All you really need is to have a sufficiently small CONFIG_NR_CPUS value
for the bit scanning optimization to be triggered, but not enough CPUs
to then actually fill that widened cpumask.  At that point, the cpumask
scanning will return the NR_CPUS constant, which is _not_ the same as
nr_cpumask_bits.

This just does the mindless fix with

   sed -i 's/== nr_cpumask_bits/>= nr_cpu_ids/'

to fix the incorrect uses.

The ones in the SCSI lpfc driver in particular could probably be fixed
more cleanly by just removing that repeated pattern entirely, but I am
not emptionally invested enough in that driver to care.

Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/lkml/481b19b5-83a0-4793-b4fd-194ad7b978c3@roeck-us.net/
Reported-and-tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/lkml/CAMuHMdUKo_Sf7TjKzcNDa8Ve+6QrK+P8nSQrSQ=6LTRmcBKNww@mail.gmail.com/
Reported-by: Vernon Yang <vernon2gm@gmail.com>
Link: https://lore.kernel.org/lkml/20230306160651.2016767-1-vernon2gm@gmail.com/
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-03-06 12:15:13 -08:00
..
selftest treewide: use get_random_u32_inclusive() when possible 2022-11-18 02:18:02 +01:00
allowedips.c wireguard: allowedips: don't corrupt stack when detecting overflow 2022-08-02 13:47:50 -07:00
allowedips.h wireguard: allowedips: free empty intermediate nodes when removing single node 2021-06-04 14:25:14 -07:00
cookie.c
cookie.h
device.c pm/sleep: Add PM_USERSPACE_AUTOSLEEP Kconfig 2022-07-01 10:39:20 +02:00
device.h wireguard: receive: use ring buffer for incoming handshakes 2021-11-29 19:50:50 -08:00
main.c wireguard: main: rename 'mod_init' & 'mod_exit' functions to be module-specific 2021-11-29 19:50:30 -08:00
Makefile wireguard: do not use -O3 2021-06-04 14:25:14 -07:00
messages.h wireguard: queueing: preserve flow hash across packet scrubbing 2020-05-20 20:55:09 -07:00
netlink.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-09-22 13:02:10 -07:00
netlink.h
noise.c lib/crypto: blake2s: move hmac construction into wireguard 2022-01-18 13:03:55 +01:00
noise.h wireguard: noise: separate receive counter from send counter 2020-05-20 20:55:09 -07:00
peer.c net: drop the weight argument from netif_napi_add 2022-09-28 18:57:14 -07:00
peer.h wireguard: peer: allocate in kmem_cache 2021-06-04 14:25:14 -07:00
peerlookup.c wireguard: peerlookup: take lock before checking hash in replace operation 2020-09-09 11:31:38 -07:00
peerlookup.h
queueing.c wireguard: queueing: use CFI-safe ptr_ring cleanup function 2022-03-30 19:14:08 -07:00
queueing.h cpumask: fix incorrect cpumask scanning result checks 2023-03-06 12:15:13 -08:00
ratelimiter.c wireguard: ratelimiter: use kvcalloc() instead of kvzalloc() 2021-11-29 19:50:50 -08:00
ratelimiter.h
receive.c wireguard: receive: use dev_sw_netstats_rx_add() 2022-06-09 21:53:10 -07:00
send.c wireguard: queueing: get rid of per-peer ring buffers 2021-02-23 15:59:34 -08:00
socket.c wireguard: socket: ignore v6 endpoints when ipv6 is disabled 2022-03-30 19:14:09 -07:00
socket.h
timers.c wireguard: timers: cast enum limits members to int in prints 2022-12-13 19:30:45 -08:00
timers.h
version.h