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From: Kees Cook <keescook@chromium.org>
To: Vijay Balakrishna <vijayb@linux.microsoft.com>
Cc: Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	John Ogness <john.ogness@linutronix.de>,
	Colin Cross <ccross@android.com>, Tony Luck <tony.luck@intel.com>,
	Anton Vorontsov <anton@enomsg.org>,
	linux-kernel@vger.kernel.org
Subject: Re: pstore/ram: printk: NULL characters in pstore ramoops area
Date: Thu, 10 Aug 2023 16:50:56 -0700	[thread overview]
Message-ID: <202308101649.337F4D8@keescook> (raw)
In-Reply-To: <0220f601-14f8-1dda-f057-73a608fbe62b@linux.microsoft.com>

On Thu, Aug 10, 2023 at 04:32:58PM -0700, Vijay Balakrishna wrote:
> On 8/4/23 00:59, Kees Cook wrote:
> > Is the issue present in modern kernels?
> 
> Yes, the issue present in mainline kernel, I can repro on a x86_64 VM with v6.5.0-rc5 kernel.
> 
> $ uname -a
> Linux vijay-vm3 6.5.0-rc5-ramoops #10 SMP PREEMPT_DYNAMIC Thu Aug 10 17:24:39 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
> $ cat /proc/cmdline
> BOOT_IMAGE=/boot/vmlinuz-6.5.0-rc5-ramoops root=UUID=xx ro mem=8188M ramoops.mem_address=0x2BFC00000 ramoops.mem_size=0x400000 ramoops.max_reason=5 ramoops.record_size=0x80000 console=tty1 console=ttyS0 earlyprintk=ttyS0 rootdelay=300
> 
> (excerpt from /var/lib/systemd/pstore/dmesg-ramoops-0 after warm reboot)
> <5>[    0.000000] Linux version 6.5.0-rc5-ramoops (vijay@vijay-vm1) (gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #10 SMP PREEMPT_DYNAMIC Thu Aug 10 17:24:39 UTC 2023
> ..
> <6>[    0.463984] Calibrating delay loop (skipped), value calculated using timer frequency.. ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@
> 
> (hex dump output)
> 
> 00003160  61 6c 63 75 6c 61 74 65  64 20 75 73 69 6e 67 20  |alculated using |
> 00003170  74 69 6d 65 72 20 66 72  65 71 75 65 6e 63 79 2e  |timer frequency.|
> 00003180  2e 20 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |. ..............|
> 00003190  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> 000031a0  00 0a 3c 36 3e 5b 20 20  20 20 30 2e 34 36 37 39  |..<6>[    0.4679|

Can you share the .config you're building with? And what are you using
to trigger an Oops? I will see if I can reproduce this...

-- 
Kees Cook

  reply	other threads:[~2023-08-10 23:51 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <f28990eb-03bc-2259-54d0-9f2254abfe62@linux.microsoft.com>
2023-08-04  7:59 ` pstore/ram: printk: NULL characters in pstore ramoops area Kees Cook
2023-08-10 23:32   ` Vijay Balakrishna
2023-08-10 23:50     ` Kees Cook [this message]
2023-08-11  0:48       ` Vijay Balakrishna
2023-08-11  3:05         ` Kees Cook
2023-08-11  3:16         ` Kees Cook
2023-08-07 17:19 ` Vijay Balakrishna
2023-08-08  8:15   ` Petr Mladek
2023-08-09  1:21     ` Vijay Balakrishna
2023-08-10  9:14       ` Petr Mladek
2023-08-11  5:23         ` Kees Cook

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