From: Vasily Gorbik gor@linux.ibm.com
commit f3122a79a1b0a113d3aea748e0ec26f2cb2889de upstream.
arch_update_cpu_topology is first called from: kernel_init_freeable->sched_init_smp->sched_init_domains
even before cpus has been registered in: kernel_init_freeable->do_one_initcall->s390_smp_init
Do not trigger kobject_uevent change events until cpu devices are actually created. Fixes the following kasan findings:
BUG: KASAN: global-out-of-bounds in kobject_uevent_env+0xb40/0xee0 Read of size 8 at addr 0000000000000020 by task swapper/0/1
BUG: KASAN: global-out-of-bounds in kobject_uevent_env+0xb36/0xee0 Read of size 8 at addr 0000000000000018 by task swapper/0/1
CPU: 0 PID: 1 Comm: swapper/0 Tainted: G B Hardware name: IBM 3906 M04 704 (LPAR) Call Trace: ([<0000000143c6db7e>] show_stack+0x14e/0x1a8) [<0000000145956498>] dump_stack+0x1d0/0x218 [<000000014429fb4c>] print_address_description+0x64/0x380 [<000000014429f630>] __kasan_report+0x138/0x168 [<0000000145960b96>] kobject_uevent_env+0xb36/0xee0 [<0000000143c7c47c>] arch_update_cpu_topology+0x104/0x108 [<0000000143df9e22>] sched_init_domains+0x62/0xe8 [<000000014644c94a>] sched_init_smp+0x3a/0xc0 [<0000000146433a20>] kernel_init_freeable+0x558/0x958 [<000000014599002a>] kernel_init+0x22/0x160 [<00000001459a71d4>] ret_from_fork+0x28/0x30 [<00000001459a71dc>] kernel_thread_starter+0x0/0x10
Cc: stable@vger.kernel.org Reviewed-by: Heiko Carstens heiko.carstens@de.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/s390/kernel/topology.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/s390/kernel/topology.c +++ b/arch/s390/kernel/topology.c @@ -311,7 +311,8 @@ int arch_update_cpu_topology(void) on_each_cpu(__arch_update_dedicated_flag, NULL, 0); for_each_online_cpu(cpu) { dev = get_cpu_device(cpu); - kobject_uevent(&dev->kobj, KOBJ_CHANGE); + if (dev) + kobject_uevent(&dev->kobj, KOBJ_CHANGE); } return rc; }