From: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/64: properly initialise the stackprotector canary on SMP.
Date: Mon, 15 Oct 2018 15:03:21 +0530 [thread overview]
Message-ID: <1539596001.28358.1.camel@abdul.in.ibm.com> (raw)
In-Reply-To: <a2694b8ffeb6c52d1c755d8a7bfaac689c4e1c6d.1539423893.git.christophe.leroy@c-s.fr>
On Sat, 2018-10-13 at 09:45 +0000, Christophe Leroy wrote:
> 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 <abdhalee@linux.vnet.ibm.com>
> Fixes: 06ec27aea9fc ("powerpc/64: add stack protector support")
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> 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 <linux/topology.h>
> #include <linux/profile.h>
> #include <linux/processor.h>
> +#include <linux/random.h>
>
> #include <asm/ptrace.h>
> #include <linux/atomic.h>
> @@ -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;
Thank you Christophe for the fix, Machine boots fine with above patch.
Reported-and-tested-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
--
Regard's
Abdul Haleem
IBM Linux Technology Centre
prev parent reply other threads:[~2018-10-15 9:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-13 9:45 [PATCH] powerpc/64: properly initialise the stackprotector canary on SMP Christophe Leroy
2018-10-15 4:01 ` Michael Ellerman
2018-10-15 9:33 ` Abdul Haleem [this message]
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