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From: Gen Zhang <blackgod016574@gmail.com>
To: Nicolas Pitre <nico@fluxnic.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] vt: Fix a missing-check bug in drivers/tty/vt/vt.c
Date: Tue, 21 May 2019 15:39:01 +0800	[thread overview]
Message-ID: <20190521073901.GF5263@zhanggen-UX430UQ> (raw)
In-Reply-To: <nycvar.YSQ.7.76.1905210022050.1558@knanqh.ubzr>

On Tue, May 21, 2019 at 12:30:38AM -0400, Nicolas Pitre wrote:
> Now imagine that MIN_NR_CONSOLES is defined to 10 instead of 1.
> 
> What happens with allocated memory if the err_vc condition is met on the 
> 5th loop?
Yes, vc->vc_screenbuf from the last loop is still not freed, right? I
don't have idea to solve this one. Could please give some advice? Since
we have to consider the err_vc condition.

> If err_vc_screenbuf condition is encountered on the 5th loop (curcons = 
> 4), what is the value of vc_cons[4].d? Isn't it the same as vc that you 
> just freed?
> 
> 
> Nicolas
Thanks for your explaination! You mean a double free situation may 
happen, right? But in vc_allocate() there is also such a kfree(vc) and 
vc_cons[currcons].d = NULL operation. This situation is really confusing
me.
Thanks
Gen

  reply	other threads:[~2019-05-21  7:39 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-21  2:29 Gen Zhang
2019-05-21  2:55 ` Nicolas Pitre
2019-05-21  3:09   ` Gen Zhang
2019-05-21  3:26     ` Nicolas Pitre
2019-05-21  4:00       ` Gen Zhang
2019-05-21  4:30         ` Nicolas Pitre
2019-05-21  7:39           ` Gen Zhang [this message]
2019-05-22  2:43             ` Nicolas Pitre
2019-05-22  8:10               ` Gen Zhang
2019-05-22 12:19               ` [PATCH v3] " Gen Zhang
2019-05-22 14:18                 ` Nicolas Pitre
2019-05-24  2:27                   ` [PATCH v3] vt: Fix a missing-check bug in con_init() Gen Zhang
2019-05-21  3:21   ` [PATCH v3] vt: Fix a missing-check bug in drivers/tty/vt/vt.c Gen Zhang
2019-05-21  6:46     ` Oleksandr Natalenko

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