[Devel] [PATCH vz7 0/5] kasan: avoid false positive reports related to stack handling

[Konstantin Khorenko]

Running LTP testsuit on debug kernel we got a KASan complain:

 ==================================================================
 BUG: KASan: out of bounds on stack in update_stack_state+0x219/0x260 at addr ffff880385997cc8
 Read of size 8 by task watchdog/12577
 page:ffffea000e1665c0 count:0 mapcount:0 mapping:          (null) index:0x0
 page flags: 0x2fffff00000000()
 page dumped because: kasan: bad access detected
 CPU: 0 PID: 12577 Comm: watchdog ve: 0 Kdump: loaded Tainted: G        W      ------------   3.10.0-862.14.4.vz7.72.14.debug #1 72.14
 Hardware name: DEPO Computers To Be Filled By O.E.M./H77 Pro4/MVP, BIOS P1.30 05/10/2012
 Call Trace:
 [<ffffffffa7fa0cd5>] dump_stack+0x19/0x1b
 [<ffffffffa6e74187>] kasan_report+0x4b7/0x4f0
 [<ffffffffa6944769>] ? update_stack_state+0x219/0x260
 [<ffffffffa6e74239>] __asan_report_load8_noabort+0x19/0x20
 [<ffffffffa6944769>] update_stack_state+0x219/0x260
 [<ffffffffa6944c2d>] __unwind_start+0x10d/0x380
 [<ffffffffa69e52a9>] ? ptrace_may_access+0x39/0x50
 [<ffffffffa68bbe2e>] __save_stack_trace+0x5e/0x100
 [<ffffffffa68bbf2c>] save_stack_trace_tsk+0x2c/0x40
 [<ffffffffa7070f75>] proc_pid_stack+0x145/0x220
 [<ffffffffa7070e30>] ? lock_trace+0xb0/0xb0
 [<ffffffffa70730fd>] proc_single_show+0xfd/0x170
 [<ffffffffa6f669d9>] seq_read+0x339/0x1290
 [<ffffffffa6f666a0>] ? single_open_size+0x130/0x130
 [<ffffffffa71312b6>] ? security_file_permission+0x136/0x190
 [<ffffffffa6ee7d3e>] ? rw_verify_area+0xbe/0x2c0
 [<ffffffffa6ee80c6>] vfs_read+0x186/0x440
 [<ffffffffa6eeb4dc>] SyS_read+0x17c/0x290
 [<ffffffffa6eeb360>] ? __kernel_write+0x450/0x450
 [<ffffffffa7fd4e8b>] ? sysret_check+0x26/0xfd
 [<ffffffffa6b6656d>] ? trace_hardirqs_on_caller+0x40d/0x5a0
 [<ffffffffa73142d0>] ? trace_hardirqs_on_thunk+0x1a/0x1c
 [<ffffffffa7fd4e5b>] system_call_fastpath+0x22/0x27
 Memory state around the buggy address:
 ffff880385997b80: 00 00 00 00 00 00 00 00 00 00 f4 00 00 00 00 00
 ffff880385997c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 >ffff880385997c80: 00 00 00 00 00 00 00 f1 f1 f1 f1 00 f4 f4 f4 f2
                                              ^
 ffff880385997d00: f2 f2 f2 00 f4 f4 f4 00 00 00 00 00 00 00 00 00
 ffff880385997d80: 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00
 ==================================================================

The real fix for this false positive is the last patch,
others are just "worth to apply".

https://jira.sw.ru/browse/HCI-171
https://pmc.acronis.com/browse/VSTOR-16798

Brian Gerst (1):
  ms/sched/x86: Add 'struct inactive_task_frame' to better document the
    sleeping task stack frame

Dmitry Vyukov (2):
  ms/kprobes: Avoid false KASAN reports during stack copy
  ms/kprobes: Unpoison stack in jprobe_return() for KASAN

Josh Poimboeuf (1):
  ms/x86/unwind: Disable KASAN checks for non-current tasks

Mark Rutland (1):
  ms/kasan: add functions to clear stack poison

 arch/x86/include/asm/stacktrace.h |  7 +++++--
 arch/x86/include/asm/switch_to.h  |  5 +++++
 arch/x86/kernel/kgdb.c            |  3 ++-
 arch/x86/kernel/kprobes/core.c    | 11 ++++++++---
 arch/x86/kernel/process.c         |  3 ++-
 arch/x86/kernel/unwind_frame.c    | 19 +++++++++++++++++--
 include/linux/kasan.h             |  8 +++++++-
 mm/kasan/kasan.c                  | 36 ++++++++++++++++++++++++++++++++++++
 8 files changed, 82 insertions(+), 10 deletions(-)

-- 
2.15.1