linux-kernel - Re: WARNING in kmalloc

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Message-ID: <20171204081408.oyp46roxbkjbxxkw@mwanda>
Date:   Mon, 4 Dec 2017 11:14:08 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Eric Biggers <ebiggers3@...il.com>
Cc:     syzbot 
        <bot+2797c18fc195e3e240c3c3e7837a14130e157fb0@...kaller.appspotmail.com>,
        adobriyan@...il.com, akpm@...ux-foundation.org, arnd@...db.de,
        dave.jiang@...el.com, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk,
        linux-block@...r.kernel.org
Subject: Re: WARNING in kmalloc_slab (3)

On Sun, Dec 03, 2017 at 12:16:08PM -0800, Eric Biggers wrote:
> Looks like BLKTRACESETUP doesn't limit the '.buf_nr' parameter, allowing anyone
> who can open a block device to cause an extremely large kmalloc.  Here's a
> simplified reproducer:
> 

There are lots of places which allow people to allocate as much as they
want.  With Syzcaller, you might want to just hard code a __GFP_NOWARN
in to disable it.

regards,
dan carpenter