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authorKees Cook2017-06-21 13:00:26 -0700
committerIngo Molnar2017-06-28 18:54:46 +0200
commitfd25d19f6b8da315332bb75936605fb45d3ea981 (patch)
tree526af3a06699d0a2570b04402548a6edc61c07bf /arch
parentf9e169883164390a15b56d00cb7e22c2e72f4dba (diff)
locking/refcount: Create unchecked atomic_t implementation
Many subsystems will not use refcount_t unless there is a way to build the kernel so that there is no regression in speed compared to atomic_t. This adds CONFIG_REFCOUNT_FULL to enable the full refcount_t implementation which has the validation but is slightly slower. When not enabled, refcount_t uses the basic unchecked atomic_t routines, which results in no code changes compared to just using atomic_t directly. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: David S. Miller <davem@davemloft.net> Cc: David Windsor <dwindsor@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Elena Reshetova <elena.reshetova@intel.com> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Hans Liljestrand <ishkamiel@gmail.com> Cc: James Bottomley <James.Bottomley@hansenpartnership.com> Cc: Jann Horn <jannh@google.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Serge E. Hallyn <serge@hallyn.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: arozansk@redhat.com Cc: axboe@kernel.dk Cc: linux-arch <linux-arch@vger.kernel.org> Link: http://lkml.kernel.org/r/20170621200026.GA115679@beast Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/Kconfig9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 6c00e5b00f8b..f76b214cf7ad 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -867,4 +867,13 @@ config STRICT_MODULE_RWX
config ARCH_WANT_RELAX_ORDER
bool
+config REFCOUNT_FULL
+ bool "Perform full reference count validation at the expense of speed"
+ help
+ Enabling this switches the refcounting infrastructure from a fast
+ unchecked atomic_t implementation to a fully state checked
+ implementation, which can be (slightly) slower but provides protections
+ against various use-after-free conditions that can be used in
+ security flaw exploits.
+
source "kernel/gcov/Kconfig"