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Jiri Kosina 10b3a32d29 random: fix accounting race condition with lockless irq entropy_count update 
Commit 902c098a36 ("random: use lockless techniques in the interrupt
path") turned IRQ path from being spinlock protected into lockless
cmpxchg-retry update.

That commit removed r->lock serialization between crediting entropy bits
from IRQ context and accounting when extracting entropy on userspace
read path, but didn't turn the r->entropy_count reads/updates in
account() to use cmpxchg as well.

It has been observed, that under certain circumstances this leads to
read() on /dev/urandom to return 0 (EOF), as r->entropy_count gets
corrupted and becomes negative, which in turn results in propagating 0
all the way from account() to the actual read() call.

Convert the accounting code to be the proper lockless counterpart of
what has been partially done by 902c098a36.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Greg KH <greg@kroah.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2013-05-24 16:22:52 -07:00
..
agp drm/i915: Disable WC PTE updates to w/a buggy IOMMU on ILK 2013-02-20 00:21:49 +01:00
hw_random drivers/char/hw_random: don't check resource with devm_ioremap_resource 2013-05-12 15:19:46 +02:00
ipmi ipmi: ipmi_devintf: compat_ioctl method fails to take ipmi_mutex 2013-05-16 13:49:25 -07:00
mwave 8250: three way resolve of the 8250 diffs 2012-07-17 09:11:50 -07:00
pcmcia Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
tpm TPM: Retry SaveState command in suspend path 2013-04-17 09:31:32 -05:00
xilinx_hwicap char: remove use of __devexit 2012-11-21 12:55:19 -08:00
Kconfig tty: Added a CONFIG_TTY option to allow removal of TTY 2013-01-18 16:15:27 -08:00
Makefile IPMI: Change link order 2012-10-16 18:07:12 -07:00
apm-emulation.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/apm 2012-04-05 17:34:30 -07:00
applicom.c applicom: use correct array offset 2013-03-15 12:23:48 -07:00
applicom.h
…
bfin-otp.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
bsr.c powerpc/BSR: cleanup the error path of bsr_init 2012-07-17 10:27:38 -07:00
ds1302.c Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
ds1620.c ds1620: single_open() leak 2013-05-05 00:11:29 -04:00
dsp56k.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
dtlk.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
efirtc.c rtc: single_open() leaks 2013-05-05 00:12:29 -04:00
generic_nvram.c drivers: fix up various ->llseek() implementations 2011-07-20 20:47:58 -04:00
genrtc.c rtc: single_open() leaks 2013-05-05 00:12:29 -04:00
hangcheck-timer.c
…
hpet.c vm: convert HPET mmap to vm_iomap_memory() helper 2013-04-19 09:46:39 -07:00
i8k.c module_param: make bool parameters really bool (drivers & misc) 2012-01-13 09:32:20 +10:30
lp.c Char: lp, protect LPGETSTATUS with port_mutex 2013-05-16 18:08:58 -07:00
mbcs.c char: remove use of __devinitconst 2012-11-21 12:55:19 -08:00
mbcs.h Fix common misspellings 2011-03-31 11:26:23 -03:00
mem.c aio: don't include aio.h in sched.h 2013-05-07 20:16:25 -07:00
misc.c drivers/char/misc.c:misc_register(): do not loop on misc_list unconditionally 2013-02-27 19:10:21 -08:00
mmtimer.c drivers/char/mmtimer.c: Remove useless kfree 2012-09-26 13:20:40 -07:00
msm_smd_pkt.c drivers/char/msm_smd_pkt.c: don't use IS_ERR() 2011-08-25 16:25:33 -07:00
mspec.c mm: kill vma flag VM_RESERVED and mm->reserved_vm counter 2012-10-09 16:22:19 +09:00
nsc_gpio.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
nvram.c Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
nwbutton.c drivers/char: removes unnecessary semicolon 2012-09-26 13:20:39 -07:00
nwbutton.h
…
nwflash.c Merge branch 'late/fixes' into fixes 2012-10-07 07:22:32 -07:00
pc8736x_gpio.c pc8736x_gpio: use platform_device_unregister in pc8736x_gpio_cleanup() 2012-10-24 15:52:29 -07:00
ppdev.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
ps3flash.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
random.c random: fix accounting race condition with lockless irq entropy_count update 2013-05-24 16:22:52 -07:00
raw.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
rtc.c drivers/char: removes unnecessary semicolon 2012-09-26 13:20:39 -07:00
scx200_gpio.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
snsc.c Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl 2010-10-22 10:52:56 -07:00
snsc.h headers: kobject.h redux 2011-01-10 08:51:44 -08:00
snsc_event.c
…
sonypi.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
tb0219.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
tile-srom.c drivers: char: Use PTR_RET function 2013-03-25 13:18:11 -07:00
tlclk.c drivers/char/tlclk.c: fix error return code 2012-08-16 10:09:15 -07:00
toshiba.c Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl 2010-10-22 10:52:56 -07:00
ttyprintk.c ttyprintk: Fix NULL pointer deref by setting tty_port ops after initializing port 2013-05-21 10:13:23 -07:00
uv_mmtimer.c BKL: remove extraneous #include <smp_lock.h> 2010-11-17 08:59:32 -08:00
virtio_console.c Lots of virtio work which wasn't quite ready for last merge window. Plus 2013-05-02 14:14:04 -07:00