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* [PATCH AUTOSEL 4.19 01/18] powerpc/kasan: Silence KASAN warnings in __get_wchan()
@ 2022-06-14  2:09 ` Sasha Levin
  0 siblings, 0 replies; 29+ messages in thread
From: Sasha Levin @ 2022-06-14  2:09 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Sasha Levin, Kees Cook, Chen Jingwen, paulus, Wanming Hu,
	linuxppc-dev, He Ying

From: He Ying <heying24@huawei.com>

[ Upstream commit a1b29ba2f2c171b9bea73be993bfdf0a62d37d15 ]

The following KASAN warning was reported in our kernel.

  BUG: KASAN: stack-out-of-bounds in get_wchan+0x188/0x250
  Read of size 4 at addr d216f958 by task ps/14437

  CPU: 3 PID: 14437 Comm: ps Tainted: G           O      5.10.0 #1
  Call Trace:
  [daa63858] [c0654348] dump_stack+0x9c/0xe4 (unreliable)
  [daa63888] [c035cf0c] print_address_description.constprop.3+0x8c/0x570
  [daa63908] [c035d6bc] kasan_report+0x1ac/0x218
  [daa63948] [c00496e8] get_wchan+0x188/0x250
  [daa63978] [c0461ec8] do_task_stat+0xce8/0xe60
  [daa63b98] [c0455ac8] proc_single_show+0x98/0x170
  [daa63bc8] [c03cab8c] seq_read_iter+0x1ec/0x900
  [daa63c38] [c03cb47c] seq_read+0x1dc/0x290
  [daa63d68] [c037fc94] vfs_read+0x164/0x510
  [daa63ea8] [c03808e4] ksys_read+0x144/0x1d0
  [daa63f38] [c005b1dc] ret_from_syscall+0x0/0x38
  --- interrupt: c00 at 0x8fa8f4
      LR = 0x8fa8cc

  The buggy address belongs to the page:
  page:98ebcdd2 refcount:0 mapcount:0 mapping:00000000 index:0x2 pfn:0x1216f
  flags: 0x0()
  raw: 00000000 00000000 01010122 00000000 00000002 00000000 ffffffff 00000000
  raw: 00000000
  page dumped because: kasan: bad access detected

  Memory state around the buggy address:
   d216f800: 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 00 00
   d216f880: f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  >d216f900: 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00
                                            ^
   d216f980: f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 00 00
   d216fa00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

After looking into this issue, I find the buggy address belongs
to the task stack region. It seems KASAN has something wrong.
I look into the code of __get_wchan in x86 architecture and
find the same issue has been resolved by the commit
f7d27c35ddff ("x86/mm, kasan: Silence KASAN warnings in get_wchan()").
The solution could be applied to powerpc architecture too.

As Andrey Ryabinin said, get_wchan() is racy by design, it may
access volatile stack of running task, thus it may access
redzone in a stack frame and cause KASAN to warn about this.

Use READ_ONCE_NOCHECK() to silence these warnings.

Reported-by: Wanming Hu <huwanming@huaweil.com>
Signed-off-by: He Ying <heying24@huawei.com>
Signed-off-by: Chen Jingwen <chenjingwen6@huawei.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220121014418.155675-1-heying24@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/kernel/process.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 02b69a68139c..56c33285b1df 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2017,12 +2017,12 @@ unsigned long get_wchan(struct task_struct *p)
 		return 0;
 
 	do {
-		sp = *(unsigned long *)sp;
+		sp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
 		if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD) ||
 		    p->state == TASK_RUNNING)
 			return 0;
 		if (count > 0) {
-			ip = ((unsigned long *)sp)[STACK_FRAME_LR_SAVE];
+			ip = READ_ONCE_NOCHECK(((unsigned long *)sp)[STACK_FRAME_LR_SAVE]);
 			if (!in_sched_functions(ip))
 				return ip;
 		}
-- 
2.35.1


^ permalink raw reply related	[flat|nested] 29+ messages in thread

end of thread, other threads:[~2022-06-14  2:25 UTC | newest]

Thread overview: 29+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-06-14  2:09 [PATCH AUTOSEL 4.19 01/18] powerpc/kasan: Silence KASAN warnings in __get_wchan() Sasha Levin
2022-06-14  2:09 ` Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 02/18] ASoC: cs42l52: Fix TLV scales for mixer controls Sasha Levin
2022-06-14  2:09   ` Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 03/18] ASoC: cs53l30: Correct number of volume levels on SX controls Sasha Levin
2022-06-14  2:09   ` Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 04/18] ASoC: cs42l52: Correct TLV for Bypass Volume Sasha Levin
2022-06-14  2:09   ` Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 05/18] ASoC: cs42l56: Correct typo in minimum level for SX volume controls Sasha Levin
2022-06-14  2:09   ` Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 06/18] ata: libata-core: fix NULL pointer deref in ata_host_alloc_pinfo() Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 07/18] ASoC: wm8962: Fix suspend while playing music Sasha Levin
2022-06-14  2:09   ` Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 08/18] ASoC: es8328: Fix event generation for deemphasis control Sasha Levin
2022-06-14  2:09   ` Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 09/18] ASoC: wm_adsp: Fix event generation for wm_adsp_fw_put() Sasha Levin
2022-06-14  2:09   ` Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 10/18] scsi: vmw_pvscsi: Expand vcpuHint to 16 bits Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 11/18] scsi: lpfc: Fix port stuck in bypassed state after LIP in PT2PT topology Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 12/18] scsi: ipr: Fix missing/incorrect resource cleanup in error case Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 13/18] scsi: pmcraid: Fix missing " Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 14/18] virtio-mmio: fix missing put_device() when vm_cmdline_parent registration failed Sasha Levin
2022-06-14  2:09   ` Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 15/18] nfc: nfcmrvl: Fix memory leak in nfcmrvl_play_deferred Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 16/18] ipv6: Fix signed integer overflow in l2tp_ip6_sendmsg Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 17/18] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag Sasha Levin
2022-06-14  2:09   ` Sasha Levin
2022-06-14  2:09   ` Sasha Levin
2022-06-14  2:09 ` [PATCH AUTOSEL 4.19 18/18] netfs: gcc-12: temporarily disable '-Wattribute-warning' for now Sasha Levin

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