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| author |   Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2018-12-06 09:32:57 +0100 |
|---|---|---|
| committer |   Kees Cook <keescook@chromium.org> | 2018-12-12 13:20:07 -0800 |
| commit | 189af4657186da08a2e79fb8e906cfd82b2ccddc (patch) | |
| tree | aef1d1ec51997c0baf5f415ad71a7929ac049746 /arch/arm/kernel/process.c | |
| parent | Linux 4.20-rc2 (diff) | |
| download | linux-dev-189af4657186da08a2e79fb8e906cfd82b2ccddc.tar.xz linux-dev-189af4657186da08a2e79fb8e906cfd82b2ccddc.zip | |
ARM: smp: add support for per-task stack canaries
On ARM, we currently only change the value of the stack canary when
switching tasks if the kernel was built for UP. On SMP kernels, this
is impossible since the stack canary value is obtained via a global
symbol reference, which means
a) all running tasks on all CPUs must use the same value
b) we can only modify the value when no kernel stack frames are live
on any CPU, which is effectively never.
So instead, use a GCC plugin to add a RTL pass that replaces each
reference to the address of the __stack_chk_guard symbol with an
expression that produces the address of the 'stack_canary' field
that is added to struct thread_info. This way, each task will use
its own randomized value.
Cc: Russell King <linux@armlinux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Emese Revfy <re.emese@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Laura Abbott <labbott@redhat.com>
Cc: kernel-hardening@lists.openwall.com
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'arch/arm/kernel/process.c')
| -rw-r--r-- | arch/arm/kernel/process.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 82ab015bf42b..16601d1442d1 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -39,7 +39,7 @@ #include <asm/tls.h> #include <asm/vdso.h> -#ifdef CONFIG_STACKPROTECTOR +#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK) #include <linux/stackprotector.h> unsigned long __stack_chk_guard __read_mostly; EXPORT_SYMBOL(__stack_chk_guard); @@ -267,6 +267,10 @@ copy_thread(unsigned long clone_flags, unsigned long stack_start, thread_notify(THREAD_NOTIFY_COPY, thread); +#ifdef CONFIG_STACKPROTECTOR_PER_TASK + thread->stack_canary = p->stack_canary; +#endif + return 0; } |