David Howells 8a004caec1 KEYS: Fix race between updating and finding a negative key ... commit 363b02dab0 upstream. Consolidate KEY_FLAG_INSTANTIATED, KEY_FLAG_NEGATIVE and the rejection error into one field such that: (1) The instantiation state can be modified/read atomically. (2) The error can be accessed atomically with the state. (3) The error isn't stored unioned with the payload pointers. This deals with the problem that the state is spread over three different objects (two bits and a separate variable) and reading or updating them atomically isn't practical, given that not only can uninstantiated keys change into instantiated or rejected keys, but rejected keys can also turn into instantiated keys - and someone accessing the key might not be using any locking. The main side effect of this problem is that what was held in the payload may change, depending on the state. For instance, you might observe the key to be in the rejected state. You then read the cached error, but if the key semaphore wasn't locked, the key might've become instantiated between the two reads - and you might now have something in hand that isn't actually an error code. The state is now KEY_IS_UNINSTANTIATED, KEY_IS_POSITIVE or a negative error code if the key is negatively instantiated. The key_is_instantiated() function is replaced with key_is_positive() to avoid confusion as negative keys are also 'instantiated'. Additionally, barriering is included: (1) Order payload-set before state-set during instantiation. (2) Order state-read before payload-read when using the key. Further separate barriering is necessary if RCU is being used to access the payload content after reading the payload pointers. Fixes: 146aa8b145 ("KEYS: Merge the type-specific data with the payload data") Reported-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2017-10-27 10:23:18 +02:00
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acpi	Merge branch 'acpi-pci'	2015-11-07 01:30:10 +01:00
asm-generic	percpu: make this_cpu_generic_read() atomic w.r.t. interrupts	2017-10-21 17:09:01 +02:00
clocksource
crypto	crypto: ahash - Fix EINPROGRESS notification callback	2017-04-21 09:30:06 +02:00
drm	drm/ttm, drm/vmwgfx: Relax permission checking when opening surfaces	2017-04-12 12:38:33 +02:00
dt-bindings	ARM: DT updates for v4.4	2015-11-10 15:06:26 -08:00
keys
kvm	KVM: arm/arm64: arch_timer: Preserve physical dist. active state on LR.active	2015-11-24 18:07:40 +01:00
linux	KEYS: Fix race between updating and finding a negative key	2017-10-27 10:23:18 +02:00
math-emu
media	videobuf2-core: Check user space planes array in dqbuf	2016-05-04 14:48:50 -07:00
memory
misc
net	sctp: potential read out of bounds in sctp_ulpevent_type_enabled()	2017-10-21 17:09:01 +02:00
pcmcia
ras
rdma	RDMA/core: Fix incorrect structure packing for booleans	2017-03-12 06:37:29 +01:00
rxrpc
scsi	scsi: libiscsi: add lock around task lists to fix list corruption regression	2017-03-26 12:13:19 +02:00
soc	ARM: at91: define LPDDR types	2017-03-12 06:37:24 +01:00
sound	ALSA: seq: Fix copy_from_user() call inside lock	2017-10-18 09:20:42 +02:00
target	iscsi-target: Fix iscsi_np reset hung task during parallel delete	2017-08-16 13:40:28 -07:00
trace	tracing: Add #undef to fix compile error	2017-03-18 19:09:57 +08:00
uapi	uapi: fix linux/mroute6.h userspace compilation errors	2017-10-21 17:09:06 +02:00
video	drm/imx: Match imx-ipuv3-crtc components using device node in platform data	2016-06-07 18:14:37 -07:00
xen	fix xen_swiotlb_dma_mmap prototype	2017-10-05 09:41:48 +02:00
Kbuild