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From:   Sven Schnelle <svens@linux.ibm.com>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tracing: fix memcpy size when copying stack entries
References: <20230612160748.4082850-1-svens@linux.ibm.com>
        <20230612123407.5ebcabdf@gandalf.local.home>
        <yt9dy1koey7h.fsf@linux.ibm.com>
        <20230613113737.1e07c892@gandalf.local.home>
        <yt9dttva8gxt.fsf@linux.ibm.com>
Date:   Wed, 12 Jul 2023 16:06:27 +0200
In-Reply-To: <yt9dttva8gxt.fsf@linux.ibm.com> (Sven Schnelle's message of
        "Wed, 14 Jun 2023 12:41:02 +0200")
Message-ID: <yt9dilap442k.fsf@linux.ibm.com>
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Hi Steven,

Sven Schnelle <svens@linux.ibm.com> writes:

> Steven Rostedt <rostedt@goodmis.org> writes:
>
>> On Tue, 13 Jun 2023 07:19:14 +0200
>> Sven Schnelle <svens@linux.ibm.com> wrote:
>>
>>> > Yes the above may be special, but your patch breaks it.  
>>> 
>>> Indeed, i'm feeling a bit stupid for sending that patch, should have
>>> used my brain during reading the source. Thanks for the explanation.
>>
>> Does this quiet the fortifier?
>> [..]
>
> No, still getting the same warning:
>
> [    2.302776] memcpy: detected field-spanning write (size 104) of single field "stack" at kernel/trace/trace.c:3178 (size 64)

BTW, i'm seeing the same error on x86 with current master when
CONFIG_FORTIFY_SOURCE=y and CONFIG_SCHED_TRACER=y:

[    3.089395] Testing tracer wakeup: 
[    3.205602] ------------[ cut here ]------------
[    3.205958] memcpy: detected field-spanning write (size 112) of single field "&entry->caller" at kernel/trace/trace.c:3173 (size 64)
[    3.205958] WARNING: CPU: 1 PID: 0 at kernel/trace/trace.c:3173 __ftrace_trace_stack+0x1d1/0x1e0
[    3.205958] Modules linked in:
[    3.205958] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.5.0-rc1-00012-g77341f6d2110-dirty #50
[    3.205958] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014
[    3.205958] RIP: 0010:__ftrace_trace_stack+0x1d1/0x1e0
[    3.205958] Code: ff ff ff b9 40 00 00 00 4c 89 f6 48 c7 c2 d8 d3 9a 82 48 c7 c7 e8 82 99 82 48 89 44 24 08 c6 05 9d 8c 30 02 01 e8 0f 88 ed ff <0f> 0b 48 8b 44 24 08 e9 f4 fe ff ff 0f 1f 00 90 90 90 90 90 90 90
[    3.205958] RSP: 0000:ffffc90000100ee0 EFLAGS: 00010086
[    3.205958] RAX: 0000000000000000 RBX: ffff8881003db034 RCX: c0000000ffffdfff
[    3.205958] RDX: 0000000000000000 RSI: 00000000ffffdfff RDI: 0000000000000001
[    3.205958] RBP: ffff8881003db03c R08: 0000000000000000 R09: ffffc90000100d88
[    3.205958] R10: 0000000000000003 R11: ffffffff83343008 R12: ffff88810007a100
[    3.205958] R13: 000000000000000e R14: 0000000000000070 R15: 0000000000000070
[    3.205958] FS:  0000000000000000(0000) GS:ffff88817bc40000(0000) knlGS:0000000000000000
[    3.205958] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    3.205958] CR2: 0000000000000000 CR3: 000000000322e000 CR4: 00000000000006e0
[    3.205958] Call Trace:
[    3.205958]  <IRQ>
[    3.205958]  ? __ftrace_trace_stack+0x1d1/0x1e0
[    3.205958]  ? __warn+0x81/0x130
[    3.205958]  ? __ftrace_trace_stack+0x1d1/0x1e0
[    3.205958]  ? report_bug+0x171/0x1a0
[    3.205958]  ? handle_bug+0x3a/0x70
[    3.205958]  ? exc_invalid_op+0x17/0x70
[    3.205958]  ? asm_exc_invalid_op+0x1a/0x20
[    3.205958]  ? __ftrace_trace_stack+0x1d1/0x1e0
[    3.205958]  probe_wakeup+0x28e/0x340
[    3.205958]  ttwu_do_activate.isra.0+0x132/0x190
[    3.205958]  sched_ttwu_pending+0x97/0x110
[    3.205958]  __flush_smp_call_function_queue+0x131/0x400
[    3.205958]  __sysvec_call_function_single+0x2d/0xd0
[    3.205958]  sysvec_call_function_single+0x65/0x80
[    3.205958]  </IRQ>
[    3.205958]  <TASK>
[    3.205958]  asm_sysvec_call_function_single+0x1a/0x20
[    3.205958] RIP: 0010:default_idle+0xf/0x20
[    3.205958] Code: 4c 01 c7 4c 29 c2 e9 72 ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d 43 5f 31 00 fb f4 <fa> c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90