From: Guenter Roeck <linux@roeck-us.net>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Petr Mladek <pmladek@suse.com>
Cc: Shreyas Joshi <shreyas.joshi@biamp.com>,
rostedt@goodmis.org, shreyasjoshi15@gmail.com,
linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] printk: handle blank console arguments passed in.
Date: Mon, 5 Oct 2020 20:35:59 -0700 [thread overview]
Message-ID: <f19c18fd-20b3-b694-5448-7d899966a868@roeck-us.net> (raw)
In-Reply-To: <20201006025935.GA597@jagdpanzerIV.localdomain>
On 10/5/20 7:59 PM, Sergey Senozhatsky wrote:
> Cc-ing Guenter,
>
> On (20/05/22 12:00), Petr Mladek wrote:
>> On Fri 2020-05-22 16:53:06, Shreyas Joshi wrote:
>>> If uboot passes a blank string to console_setup then it results in a trashed memory.
>>> Ultimately, the kernel crashes during freeing up the memory. This fix checks if there
>>> is a blank parameter being passed to console_setup from uboot.
>>> In case it detects that the console parameter is blank then
>>> it doesn't setup the serial device and it gracefully exits.
>>>
>>> Signed-off-by: Shreyas Joshi <shreyas.joshi@biamp.com>
>>> ---
>>> V1:
>>> Fixed console_loglevel to default as per the review comments
>>>
>>> kernel/printk/printk.c | 5 ++++-
>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
>>> index ad4606234545..e9ad730991e0 100644
>>> --- a/kernel/printk/printk.c
>>> +++ b/kernel/printk/printk.c
>>> @@ -2165,7 +2165,10 @@ static int __init console_setup(char *str)
>>> char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */
>>> char *s, *options, *brl_options = NULL;
>>> int idx;
>>> -
>>> + if (str[0] == 0) {
>>> + return 1;
>>> + }
>>> if (_braille_console_setup(&str, &brl_options))
>>> return 1;
>>
>> I have fixed formatting and pushed it into printk/linux.git,
>> branch for-5.8.
>
> Petr, this patch's causing regressions for us. We use blank console= boot
> param to bypass dts. It appears that it'd be better to revert the change.
>
Not just to bypass dts, it was also possible to use console= to disable consoles
passed as config option, as well as other default console options. A quick test
confirms that this affects all platforms/architectures, not just Chromebooks.
Prior to this patch, it was possible to disable a default console with an
empty "console=" parameter. This is no longer possible. This means that
this patch results in a substantial (and, as far as I can see, completely
undiscussed) functionality change.
I don't understand why (yet), but the patch also causes regressions with
seemingly unrelated functionality, specifically with dm-verity on at least
one Chromebook platform. I filed crbug.com/1135157 to track the problem,
and reverted the patch from all our stable releases immediately after
the last round of stable release merges.
On a side note, I don't see the problem presumably fixed with this
patch in any of my tests.
Guenter
next prev parent reply other threads:[~2020-10-06 3:36 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-09 5:29 [PATCH] printk: handle blank console arguments passed in Shreyas Joshi
2020-03-17 1:34 ` Shreyas Joshi
2020-03-17 1:39 ` Steven Rostedt
2020-03-17 2:01 ` Sergey Senozhatsky
2020-03-17 2:17 ` Shreyas Joshi
2020-03-17 8:22 ` Sergey Senozhatsky
2020-05-22 6:46 ` Shreyas Joshi
2020-05-22 6:53 ` Shreyas Joshi
2020-05-22 10:00 ` Petr Mladek
2020-10-06 2:59 ` Sergey Senozhatsky
2020-10-06 3:35 ` Guenter Roeck [this message]
2020-10-06 5:08 ` Greg Kroah-Hartman
2020-10-06 11:17 ` Guenter Roeck
2020-10-06 6:59 ` Sergey Senozhatsky
2020-10-06 9:54 ` Petr Mladek
2020-10-06 13:33 ` Sergey Senozhatsky
2020-10-06 14:22 ` Guenter Roeck
2020-10-06 16:08 ` Sergey Senozhatsky
2020-10-06 9:52 ` Petr Mladek
2020-10-06 10:45 ` Guenter Roeck
2020-10-06 13:43 ` Petr Mladek
2020-10-06 16:35 ` Petr Mladek
2020-10-06 17:15 ` Sergey Senozhatsky
2020-10-07 7:28 ` Petr Mladek
2020-10-07 12:30 ` Sergey Senozhatsky
2020-10-07 14:39 ` Sergey Senozhatsky
2020-10-07 15:57 ` Guenter Roeck
2020-10-07 16:29 ` Sergey Senozhatsky
2020-10-08 5:52 ` Sergey Senozhatsky
2020-10-08 9:01 ` Petr Mladek
2020-10-08 10:56 ` Sergey Senozhatsky
2020-10-08 12:05 ` Sergey Senozhatsky
2020-10-22 11:38 ` Petr Mladek
2020-10-22 13:32 ` Sergey Senozhatsky
2020-10-08 8:50 ` Petr Mladek
2020-10-08 12:20 ` Sergey Senozhatsky
2020-10-08 12:37 ` Sergey Senozhatsky
2020-05-15 15:24 ` Petr Mladek
2020-05-20 11:50 ` Sergey Senozhatsky
2020-05-22 6:40 ` Shreyas Joshi
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