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| author | Michael Ellerman <mpe@ellerman.id.au> | 2018-10-19 08:19:10 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2018-10-21 11:32:00 +0300 |
| commit | b6aeddea74b08518289fc86545297cf18a0b53a7 (patch) | |
| tree | a17094b76504cb415992b6c57ff16c8318ee79f0 /arch/powerpc | |
| parent | daf00ae71dad8aa05965713c62558aeebf2df48e (diff) | |
| download | linux-b6aeddea74b08518289fc86545297cf18a0b53a7.tar.xz | |
powerpc: Fix stack protector crashes on CPU hotplug
Recently in commit 7241d26e8175 ("powerpc/64: properly initialise
the stackprotector canary on SMP.") we fixed a crash with stack
protector on SMP by initialising the stack canary in
cpu_idle_thread_init().
But this can also causes crashes, when a CPU comes back online after
being offline:
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: pnv_smp_cpu_kill_self+0x2a0/0x2b0
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.0-rc3-gcc-7.3.1-00168-g4ffe713b7587 #94
Call Trace:
dump_stack+0xb0/0xf4 (unreliable)
panic+0x144/0x328
__stack_chk_fail+0x2c/0x30
pnv_smp_cpu_kill_self+0x2a0/0x2b0
cpu_die+0x48/0x70
arch_cpu_idle_dead+0x20/0x40
do_idle+0x274/0x390
cpu_startup_entry+0x38/0x50
start_secondary+0x5e4/0x600
start_secondary_prolog+0x10/0x14
Looking at the stack we see that the canary value in the stack frame
doesn't match the canary in the task/paca. That is because we have
reinitialised the task/paca value, but then the CPU coming online has
returned into a function using the old canary value. That causes the
comparison to fail.
Instead we can call boot_init_stack_canary() from start_secondary()
which never returns. This is essentially what the generic code does in
cpu_startup_entry() under #ifdef X86, we should make that non-x86
specific in a future patch.
Fixes: 7241d26e8175 ("powerpc/64: properly initialise the stackprotector canary on SMP.")
Reported-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/kernel/smp.c | 10 |
1 files changed, 3 insertions, 7 deletions
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 8e3a5da24d59..3f15edf25a0d 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -35,6 +35,7 @@ #include <linux/profile.h> #include <linux/processor.h> #include <linux/random.h> +#include <linux/stackprotector.h> #include <asm/ptrace.h> #include <linux/atomic.h> @@ -1014,16 +1015,9 @@ 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; @@ -1316,6 +1310,8 @@ void start_secondary(void *unused) notify_cpu_starting(cpu); set_cpu_online(cpu, true); + boot_init_stack_canary(); + local_irq_enable(); /* We can enable ftrace for secondary cpus now */ |