From: Greg KH <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org,
alan@lxorguk.ukuu.org.uk, Peter Korsgaard <jacmet@sunsite.dk>,
George Pontis <GPontis@z9.com>,
Nicolas Ferre <nicolas.ferre@atmel.com>,
Herbert Xu <herbert@gondor.hengli.com.au>
Subject: [ 12/42] hwrng: atmel-rng - fix race condition leading to repeated bits
Date: Thu, 14 Jun 2012 16:56:35 -0700 [thread overview]
Message-ID: <20120614235624.973120740@linuxfoundation.org> (raw)
In-Reply-To: <20120614235636.GA5275@kroah.com>
3.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Korsgaard <jacmet@sunsite.dk>
commit 121daad8fd1dce63076fa55aaedd5dc3f981b334 upstream.
Data valid gets cleared by reading the ISR (status register) and NOT from
reading ODATA (data register). A new data word can become available between
checking ISR and reading ODATA, causing us to reuse the same data word next
time atmel_trng_read() gets called, if that happens before the following
data word is ready.
With this fixed, rngtest no longer complains of 'Continous run' errors.
Before:
rngtest -c 1000 < /dev/hwrng
rngtest 3
Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions. There is NO warr.
rngtest: starting FIPS tests...
rngtest: bits received from input: 20000032
rngtest: FIPS 140-2 successes: 923
rngtest: FIPS 140-2 failures: 77
rngtest: FIPS 140-2(2001-10-10) Monobit: 0
rngtest: FIPS 140-2(2001-10-10) Poker: 0
rngtest: FIPS 140-2(2001-10-10) Runs: 1
rngtest: FIPS 140-2(2001-10-10) Long run: 0
rngtest: FIPS 140-2(2001-10-10) Continuous run: 76
rngtest: input channel speed: (min=721.402; avg=46003.510; max=49321.338)Kibitss
rngtest: FIPS tests speed: (min=11.442; avg=12.714; max=12.801)Mibits/s
rngtest: Program run time: 1931860 microseconds
After:
rngtest -c 1000 < /dev/hwrng
rngtest 3
Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions. There is NO warr.
rngtest: starting FIPS tests...
rngtest: bits received from input: 20000032
rngtest: FIPS 140-2 successes: 1000
rngtest: FIPS 140-2 failures: 0
rngtest: FIPS 140-2(2001-10-10) Monobit: 0
rngtest: FIPS 140-2(2001-10-10) Poker: 0
rngtest: FIPS 140-2(2001-10-10) Runs: 0
rngtest: FIPS 140-2(2001-10-10) Long run: 0
rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
rngtest: input channel speed: (min=777.518; avg=36988.482; max=43115.342)Kibitss
rngtest: FIPS tests speed: (min=11.951; avg=12.715; max=12.887)Mibits/s
rngtest: Program run time: 2035543 microseconds
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Reported-by: George Pontis <GPontis@z9.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/hw_random/atmel-rng.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -36,6 +36,13 @@ static int atmel_trng_read(struct hwrng
/* data ready? */
if (readl(trng->base + TRNG_ODATA) & 1) {
*data = readl(trng->base + TRNG_ODATA);
+ /*
+ ensure data ready is only set again AFTER the next data
+ word is ready in case it got set between checking ISR
+ and reading ODATA, so we don't risk re-reading the
+ same word
+ */
+ readl(trng->base + TRNG_ISR);
return 4;
} else
return 0;
next prev parent reply other threads:[~2012-06-14 23:59 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-14 23:56 [ 00/42] 3.4.3-stable review Greg KH
2012-06-14 23:56 ` [ 01/42] drm/nouveau/disp: fix dithering not being enabled on some eDP macbooks Greg KH
2012-06-14 23:56 ` [ 02/42] drm/i915: Reset last_retired_head when resetting ring Greg KH
2012-06-14 23:56 ` [ 03/42] char/agp: add another Ironlake host bridge Greg KH
2012-06-14 23:56 ` [ 04/42] btree: fix tree corruption in btree_get_prev() Greg KH
2012-06-14 23:56 ` [ 05/42] powerpc/time: Sanity check of decrementer expiration is necessary Greg KH
2012-06-14 23:56 ` [ 06/42] powerpc: Fix kernel panic during kernel module load Greg KH
2012-06-14 23:56 ` [ 07/42] module_param: stop double-calling parameters Greg KH
2012-06-14 23:56 ` [ 08/42] timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond Greg KH
2012-06-14 23:56 ` [ 09/42] ext4: fix the free blocks calculation for ext3 file systems w/ uninit_bg Greg KH
2012-06-14 23:56 ` [ 10/42] x86/uv: Fix UV2 BAU legacy mode Greg KH
2012-06-14 23:56 ` [ 11/42] x86, MCE, AMD: Make APIC LVT thresholding interrupt optional Greg KH
2012-06-14 23:56 ` Greg KH [this message]
2012-06-14 23:56 ` [ 13/42] crypto: aesni-intel - fix unaligned cbc decrypt for x86-32 Greg KH
2012-06-14 23:56 ` [ 14/42] drm/ttm: Fix buffer object metadata accounting regression v2 Greg KH
2012-06-14 23:56 ` [ 15/42] Btrfs: fall back to non-inline if we dont have enough space Greg KH
2012-06-14 23:56 ` [ 16/42] iwlwifi: disable WoWLAN if !CONFIG_PM_SLEEP Greg KH
2012-06-14 23:56 ` [ 17/42] iwlwifi: unregister LEDs if mac80211 registration fails Greg KH
2012-06-14 23:56 ` [ 18/42] iwlwifi: dont mess up the SCD when removing a key Greg KH
2012-06-14 23:56 ` [ 19/42] iwlwifi: disable the buggy chain extension feature in HW Greg KH
2012-06-14 23:56 ` [ 20/42] mac80211: fix error in station state transitions during reconfig Greg KH
2012-06-14 23:56 ` [ 21/42] mac80211: clean up remain-on-channel on interface stop Greg KH
2012-06-14 23:56 ` [ 22/42] mac80211: fix non RCU-safe sta_list manipulation Greg KH
2012-06-14 23:56 ` [ 23/42] ASoC: wm8994: Ensure all AIFnCLK events are run from the _late variants Greg KH
2012-06-14 23:56 ` [ 24/42] ASoC: wm8994: Apply volume updates with clocks enabled Greg KH
2012-06-14 23:56 ` [ 25/42] bcma: add ext PA workaround for BCM4331 and BCM43431 Greg KH
2012-06-14 23:56 ` [ 26/42] ALSA: HDA: Pin fixup for Zotac Z68 motherboard Greg KH
2012-06-14 23:56 ` [ 27/42] cfg80211: fix interface combinations check Greg KH
2012-06-14 23:56 ` [ 28/42] rt2x00: use atomic variable for seqno Greg KH
2012-06-14 23:56 ` [ 29/42] wireless: rt2x00: rt2800usb add more devices ids Greg KH
2012-06-14 23:56 ` [ 30/42] wireless: rt2x00: rt2800usb more devices were identified Greg KH
2012-06-14 23:56 ` [ 31/42] net: sierra_net: device IDs for Aircard 320U++ Greg KH
2012-06-14 23:56 ` [ 32/42] can: c_can: fix "BUG! echo_skb is occupied!" during transmit Greg KH
2012-06-14 23:56 ` [ 33/42] can: c_can: fix an interrupt thrash issue with c_can driver Greg KH
2012-06-14 23:56 ` [ 34/42] can: c_can: fix race condition in c_can_open() Greg KH
2012-06-14 23:56 ` [ 35/42] gma500: dont register the ACPI video bus Greg KH
2012-06-14 23:56 ` [ 36/42] acpi_video: fix leaking PCI references Greg KH
2012-06-14 23:57 ` [ 37/42] sched: Fix the relax_domain_level boot parameter Greg KH
2012-06-14 23:57 ` [ 38/42] drm/radeon: fix tiling and command stream checking on evergreen v3 Greg KH
2012-06-14 23:57 ` [ 39/42] drm/i915: Mark the ringbuffers as being in the GTT domain Greg KH
2012-06-14 23:57 ` [ 40/42] fuse: fix stat call on 32 bit platforms Greg KH
2012-06-14 23:57 ` [ 41/42] libata: add a host flag to ignore detected ATA devices Greg KH
2012-06-14 23:57 ` [ 42/42] ata_piix: defer disks to the Hyper-V drivers by default Greg KH
2012-06-15 11:16 ` From all Hyper-V admins: Big thanks! Re: [ 41/42] libata + [ 42/42] ata_piix: defer disks to the Hyper-V drivers by default has been added to the 3.4-stable tree Victor Miasnikov
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