linux-kernel - Re: [PATCH 8/8] xen/hvc: replace BUG

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Message-ID: <e62b12e7-6dbe-3d26-2196-9cbc2c0d4160@suse.com>
Date:   Thu, 13 May 2021 12:20:35 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        xen-devel@...ts.xenproject.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>
Subject: Re: [PATCH 8/8] xen/hvc: replace BUG_ON() with negative return value

On 13.05.21 12:16, Christophe Leroy wrote:
> 
> 
> Le 13/05/2021 à 12:03, Juergen Gross a écrit :
>> Xen frontends shouldn't BUG() in case of illegal data received from
>> their backends. So replace the BUG_ON()s when reading illegal data from
>> the ring page with negative return values.
>>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
>> ---
>>   drivers/tty/hvc/hvc_xen.c | 15 +++++++++++++--
>>   1 file changed, 13 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
>> index 92c9a476defc..30d7ffb1e04c 100644
>> --- a/drivers/tty/hvc/hvc_xen.c
>> +++ b/drivers/tty/hvc/hvc_xen.c
>> @@ -86,6 +86,11 @@ static int __write_console(struct xencons_info 
>> *xencons,
>>       cons = intf->out_cons;
>>       prod = intf->out_prod;
>>       mb();            /* update queue values before going on */
>> +
>> +    if (WARN_ONCE((prod - cons) > sizeof(intf->out),
>> +              "Illegal ring page indices"))
>> +        return -EINVAL;
>> +
>>       BUG_ON((prod - cons) > sizeof(intf->out));
> 
> Why keep the BUG_ON() ?

Oh, failed to delete it. Thanks for noticing.


Juergen

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