From 7241d26e8175e95290a6549a470c330dbfc63442 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Sat, 13 Oct 2018 09:45:12 +0000 Subject: [PATCH] powerpc/64: properly initialise the stackprotector canary on SMP. commit 06ec27aea9fc ("powerpc/64: add stack protector support") doesn't initialise the stack canary on SMP secondary CPU's paca, leading to the following false positive report from the stack protector. smp: Bringing up secondary CPUs ... Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: __schedule+0x978/0xa80 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.0-rc7-next-20181010-autotest-autotest #1 Call Trace: [c000001fed5b3bf0] [c000000000a0ef3c] dump_stack+0xb0/0xf4 (unreliable) [c000001fed5b3c30] [c0000000000f9d68] panic+0x140/0x308 [c000001fed5b3cc0] [c0000000000f9844] __stack_chk_fail+0x24/0x30 [c000001fed5b3d20] [c000000000a2c3a8] __schedule+0x978/0xa80 [c000001fed5b3e00] [c000000000a2c9b4] schedule_idle+0x34/0x60 [c000001fed5b3e30] [c00000000013d344] do_idle+0x224/0x3d0 [c000001fed5b3ec0] [c00000000013d6e0] cpu_startup_entry+0x30/0x50 [c000001fed5b3ef0] [c000000000047f34] start_secondary+0x4d4/0x520 [c000001fed5b3f90] [c00000000000b370] start_secondary_prolog+0x10/0x14 This patch properly initialises the stack_canary of the secondary idle tasks. Reported-by: Abdul Haleem Fixes: 06ec27aea9fc ("powerpc/64: add stack protector support") Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/smp.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 61c1fadbc644..e774d3bf3a03 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include @@ -810,9 +811,16 @@ static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle) { struct thread_info *ti = task_thread_info(idle); +#ifdef CONFIG_STACKPROTECTOR + idle->stack_canary = get_random_canary(); +#endif + #ifdef CONFIG_PPC64 paca_ptrs[cpu]->__current = idle; paca_ptrs[cpu]->kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD; +#ifdef CONFIG_STACKPROTECTOR + paca_ptrs[cpu]->canary = idle->stack_canary; +#endif #endif ti->cpu = cpu; secondary_ti = current_set[cpu] = ti; -- 2.45.2