linux-kernel - Re: [PATCH RFC v3 4/7] epoll: Add implementation for epoll_ctl

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Message-ID: <20150215053151.GA6093@fam-t430.nay.redhat.com>
Date:	Sun, 15 Feb 2015 13:31:51 +0800
From:	Fam Zheng <famz@...hat.com>
To:	Dan Rosenberg <dan.j.rosenberg@...il.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC v3 4/7] epoll: Add implementation for epoll_ctl_batch

On Fri, 02/13 19:06, Dan Rosenberg wrote:
> 
> > +	if (ncmds <= 0 || !cmds)
> > +		return -EINVAL;
> > +	cmd_size = sizeof(struct epoll_ctl_cmd) * ncmds;
> > +	kcmds = kmalloc(cmd_size, GFP_KERNEL);
> You should probably fix the integer overflow in the calculation of the
> cmd_size variable, unless you like root vulnerabilities.
> 

Thanks! In the case of multiply overflow, we allocate a buffer that is smaller
than we think, and consequent writings will corrupt kernel memory after it.
That is the root vulnerabilities here. Will fix!

Fam
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