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Tsirkin" To: Harshit Mogalapalli Cc: error27@gmail.com, harshit.m.mogalapalli@gmail.com, Jason Wang , Xie Yongji , Gautam Dawar , Maxime Coquelin , Guanjun , Parav Pandit , Eli Cohen , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] vduse: Fix a possible warning in vduse_create_dev() Message-ID: <20221126181822-mutt-send-email-mst@kernel.org> References: <20221126040000.775914-1-harshit.m.mogalapalli@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221126040000.775914-1-harshit.m.mogalapalli@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 25, 2022 at 07:59:58PM -0800, Harshit Mogalapalli wrote: > As 'dev->vq_num' is user-controlled data, if user tries to allocate > memory larger than(>=) MAX_ORDER, then kcalloc() will fail, it > creates a stack trace and messes up dmesg with a warning. > > Call trace: > -> vduse_ioctl > --> vduse_create_dev > 'config->vq_num' is user data as it comes from ioctl, which is > assigned to 'dev->vq_num'. > > Add __GFP_NOWARN in order to avoid too large allocation warning. > This is detected by static analysis using smatch. > > Fixes: c8a6153b6c59 ("vduse: Introduce VDUSE - vDPA Device in Userspace") > Signed-off-by: Harshit Mogalapalli > --- > drivers/vdpa/vdpa_user/vduse_dev.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c > index 35dceee3ed56..5e9546b16165 100644 > --- a/drivers/vdpa/vdpa_user/vduse_dev.c > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c > @@ -1512,7 +1512,8 @@ static int vduse_create_dev(struct vduse_dev_config *config, > dev->config_size = config->config_size; > dev->vq_align = config->vq_align; > dev->vq_num = config->vq_num; > - dev->vqs = kcalloc(dev->vq_num, sizeof(*dev->vqs), GFP_KERNEL); > + dev->vqs = kcalloc(dev->vq_num, sizeof(*dev->vqs), > + GFP_KERNEL | __GFP_NOWARN); > if (!dev->vqs) > goto err_vqs; This is insufficient - the real source of the problem is that vq_num is not validated. The thing to do is to validate config and limit vq_num to 0xffff; > -- > 2.38.1