linux/include
Cesar Eduardo Barros 620c41147d crypto: more robust crypto_memneq
commit fe8c8a1268 upstream.

[Only use the compiler.h portion of this patch, to get the
OPTIMIZER_HIDE_VAR() macro, which we need for other -stable patches
- gregkh]

Disabling compiler optimizations can be fragile, since a new
optimization could be added to -O0 or -Os that breaks the assumptions
the code is making.

Instead of disabling compiler optimizations, use a dummy inline assembly
(based on RELOC_HIDE) to block the problematic kinds of optimization,
while still allowing other optimizations to be applied to the code.

The dummy inline assembly is added after every OR, and has the
accumulator variable as its input and output. The compiler is forced to
assume that the dummy inline assembly could both depend on the
accumulator variable and change the accumulator variable, so it is
forced to compute the value correctly before the inline assembly, and
cannot assume anything about its value after the inline assembly.

This change should be enough to make crypto_memneq work correctly (with
data-independent timing) even if it is inlined at its call sites. That
can be done later in a followup patch.

Compile-tested on x86_64.

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.eti.br>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-14 08:47:55 -08:00
..
acpi ACPI / hotplug: Fix conflicted PCI bridge notify handlers 2013-12-04 10:57:04 -08:00
asm-generic mm: use paravirt friendly ops for NUMA hinting ptes 2014-05-30 21:52:12 -07:00
clocksource clocksource: arch_timer: use virtual counters 2014-01-09 12:24:26 -08:00
crypto crypto: scatterwalk - Use sg_chain_ptr on chain entries 2013-12-11 22:36:29 -08:00
drm drm/radeon: add additional SI pci ids 2014-09-05 16:28:36 -07:00
dt-bindings
keys
linux crypto: more robust crypto_memneq 2014-11-14 08:47:55 -08:00
math-emu
media media: vb2: fix VBI/poll regression 2014-10-09 12:18:42 -07:00
memory
misc
net sctp: handle association restarts when the socket is closed. 2014-10-15 08:31:57 +02:00
pcmcia
ras
rdma
rxrpc
scsi scsi: fix our current target reap infrastructure 2014-05-30 21:52:11 -07:00
sound ALSA: control: Protect user controls against concurrent access 2014-06-26 15:12:43 -04:00
target target: Report correct response length for some commands 2014-06-30 20:09:45 -07:00
trace tracing: Fix syscall_*regfunc() vs copy_process() race 2014-07-06 18:54:16 -07:00
uapi ALSA: compress: Cancel the optimization of compiler and fix the size of struct for all platform. 2014-06-26 15:12:41 -04:00
video Merge branch 'fbdev-3.10-fixes' of git://gitorious.org/linux-omap-dss2/linux into linux-fbdev/for-3.10-fixes 2013-05-29 17:00:34 +08:00
xen xenbus: delay xenbus frontend resume if xenstored is not running 2013-05-29 09:04:19 -04:00
Kbuild UAPI: remove empty Kbuild files 2013-04-30 17:04:09 -07:00