Re: KASAN: use-after-free Read in task_is_descendant
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: 2018-10-21 07:13:16
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On 2018/10/21 16:10, syzbot wrote:
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:188 [inline] BUG: KASAN: use-after-free in task_is_descendant.part.2+0x610/0x670 security/yama/yama_lsm.c:295 Read of size 8 at addr ffff8801c4666b20 by task syz-executor3/12722 CPU: 1 PID: 12722 Comm: syz-executor3 Not tainted 4.19.0-rc8+ #70 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 __read_once_size include/linux/compiler.h:188 [inline] task_is_descendant.part.2+0x610/0x670 security/yama/yama_lsm.c:295
Do we need to hold write_lock_irq(&tasklist_lock); rather than rcu_read_lock(); when accessing "struct task_struct"->real_parent ?