From: "Arnd Bergmann" <arnd@arndb.de>
To: "Dan Carpenter" <error27@gmail.com>, oe-kbuild@lists.linux.dev
Cc: "kernel test robot" <lkp@intel.com>,
oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org,
"Juergen Gross" <jgross@suse.com>,
xen-devel@lists.xenproject.org,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Oleksandr Tyshchenko" <oleksandr_tyshchenko@epam.com>
Subject: Re: drivers/xen/gntdev.c:817 gntdev_get_page() warn: mask and shift to zero: expr='(addr & ~(~((1 << 12) - 1))) >> 12'
Date: Fri, 25 Sep 2026 08:43:54 +0200 [thread overview]
Message-ID: <94cbe491-1b32-47ec-a9b5-bed69bc4d52c@app.fastmail.com> (raw)
In-Reply-To: <202609241805.VsLzGPLn-lkp@intel.com>
On Thu, Sep 24, 2026, at 21:39, Dan Carpenter wrote:
> 489 return -EFAULT;
> 490 break;
> 491 case 2:
> 492 if (copy_from_user(&m, udata, sizeof(struct
> privcmd_mmapbatch_v2)))
> 493 return -EFAULT;
> 494 /* Returns per-frame error code in m.err. */
> 495 if (!access_ok(m.err, m.num * (sizeof(*m.err))))
> ^^^^^^^^^^^^^^^^^^^^^^^
> These integer overflow bugs are from 2012, but I guess your patch
> exposed
> the arm32 build to the zero day bot. The bugs only affect 32bit
> systems.
Right, the randconfig came up with an ARMv6 Xen build, which was not
possible before my patch. I'm sure this was reported for other configs
before and just showed up as introduced by my patch here.
This is clearly a bug but it does look harmless to me, as it only
results in the userspace corrupting itself when passing invalid
data.
Arnd
next prev parent reply other threads:[~2026-09-25 6:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-24 19:39 Dan Carpenter
2026-09-25 6:43 ` Arnd Bergmann [this message]
2026-09-25 7:42 ` Dan Carpenter
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