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Tsirkin" To: Jason Wang Subject: Re: [PATCH net-next 1/5] virtio_net: Fix an unsafe reference to the page chain Message-ID: <20230528022737-mutt-send-email-mst@kernel.org> References: <20230526054621.18371-1-liangchen.linux@gmail.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: xuanzhuo@linux.alibaba.com, linux-kernel@vger.kernel.org, alexander.duyck@gmail.com, virtualization@lists.linux-foundation.org, edumazet@google.com, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, davem@davemloft.net X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" T24gRnJpLCBNYXkgMjYsIDIwMjMgYXQgMDI6Mzg6NTRQTSArMDgwMCwgSmFzb24gV2FuZyB3cm90 ZToKPiBPbiBGcmksIE1heSAyNiwgMjAyMyBhdCAxOjQ24oCvUE0gTGlhbmcgQ2hlbiA8bGlhbmdj aGVuLmxpbnV4QGdtYWlsLmNvbT4gd3JvdGU6Cj4gPgo+ID4gInByaXZhdGUiIG9mIGJ1ZmZlciBw YWdlIGlzIGN1cnJlbnRseSB1c2VkIGZvciBiaWcgbW9kZSB0byBjaGFpbiBwYWdlcy4KPiA+IEJ1 dCBpbiBtZXJnZWFibGUgbW9kZSwgdGhhdCBvZmZzZXQgb2YgcGFnZSBjb3VsZCBtZWFuIHNvbWV0 aGluZyBlbHNlLAo+ID4gZS5nLiB3aGVuIHBhZ2VfcG9vbCBwYWdlIGlzIHVzZWQgaW5zdGVhZC4g U28gZXhjbHVkaW5nIG1lcmdlYWJsZSBtb2RlIHRvCj4gPiBhdm9pZCBzdWNoIGEgcHJvYmxlbS4K PiAKPiBJZiB0aGlzIGlzc3VlIGhhcHBlbnMgb25seSBpbiB0aGUgY2FzZSBvZiBwYWdlX3Bvb2ws IGl0IHdvdWxkIGJlCj4gYmV0dGVyIHRvIHNxdWFzaCBpdCB0aGVyZS4KPiAKPiBUaGFua3MKCgpU aGlzIGlzIGEgdGlueSBwYXRjaCBzbyBJIGRvbid0IGNhcmUuIEdlbmVyYWxseSBpdCdzIG9rCnRv IGZpcnN0IHJld29yayBjb2RlIHRoZW4gY2hhbmdlIGZ1bmN0aW9uYWxpdHkuCmluIHRoaXMgY2Fz ZSB3aGF0IEphc29uIHNheXMgb3MgcmlnaHQgZXNwZWNpYWxseSBiZWNhdXNlCnlvdSB0aGVuIGRv IG5vdCBuZWVkIHRvIGV4cGxhaW4gdGhhdCBjdXJyZW50IGNvZGUgaXMgb2suCgo+ID4KPiA+IFNp Z25lZC1vZmYtYnk6IExpYW5nIENoZW4gPGxpYW5nY2hlbi5saW51eEBnbWFpbC5jb20+Cj4gPiAt LS0KPiA+ICBkcml2ZXJzL25ldC92aXJ0aW9fbmV0LmMgfCAyICstCj4gPiAgMSBmaWxlIGNoYW5n ZWQsIDEgaW5zZXJ0aW9uKCspLCAxIGRlbGV0aW9uKC0pCj4gPgo+ID4gZGlmZiAtLWdpdCBhL2Ry aXZlcnMvbmV0L3ZpcnRpb19uZXQuYyBiL2RyaXZlcnMvbmV0L3ZpcnRpb19uZXQuYwo+ID4gaW5k ZXggNWE3ZjdhNzZiOTIwLi5jNWRjYTBkOTJlNjQgMTAwNjQ0Cj4gPiAtLS0gYS9kcml2ZXJzL25l dC92aXJ0aW9fbmV0LmMKPiA+ICsrKyBiL2RyaXZlcnMvbmV0L3ZpcnRpb19uZXQuYwo+ID4gQEAg LTQ5Nyw3ICs0OTcsNyBAQCBzdGF0aWMgc3RydWN0IHNrX2J1ZmYgKnBhZ2VfdG9fc2tiKHN0cnVj dCB2aXJ0bmV0X2luZm8gKnZpLAo+ID4gICAgICAgICAgICAgICAgICAgICAgICAgcmV0dXJuIE5V TEw7Cj4gPgo+ID4gICAgICAgICAgICAgICAgIHBhZ2UgPSAoc3RydWN0IHBhZ2UgKilwYWdlLT5w cml2YXRlOwo+ID4gLSAgICAgICAgICAgICAgIGlmIChwYWdlKQo+ID4gKyAgICAgICAgICAgICAg IGlmICghdmktPm1lcmdlYWJsZV9yeF9idWZzICYmIHBhZ2UpCj4gPiAgICAgICAgICAgICAgICAg ICAgICAgICBnaXZlX3BhZ2VzKHJxLCBwYWdlKTsKPiA+ICAgICAgICAgICAgICAgICBnb3RvIG9r Owo+ID4gICAgICAgICB9Cj4gPiAtLQo+ID4gMi4zMS4xCj4gPgoKX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX18KVmlydHVhbGl6YXRpb24gbWFpbGluZyBsaXN0 ClZpcnR1YWxpemF0aW9uQGxpc3RzLmxpbnV4LWZvdW5kYXRpb24ub3JnCmh0dHBzOi8vbGlzdHMu bGludXhmb3VuZGF0aW9uLm9yZy9tYWlsbWFuL2xpc3RpbmZvL3ZpcnR1YWxpemF0aW9u From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35C81C7EE29 for ; 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Sat, 27 May 2023 23:29:07 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6oMIRa2O5snnR2DBaZbn6UNByaPav76lWPUnAJoPlC/LhnJ393xJpdpLpMJQpzMKIgXPhbhw== X-Received: by 2002:a7b:cc95:0:b0:3f5:1a4:a08d with SMTP id p21-20020a7bcc95000000b003f501a4a08dmr7162208wma.7.1685255347442; Sat, 27 May 2023 23:29:07 -0700 (PDT) Received: from redhat.com ([2.52.146.27]) by smtp.gmail.com with ESMTPSA id z10-20020a7bc7ca000000b003f602e2b653sm13856777wmk.28.2023.05.27.23.29.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 27 May 2023 23:29:06 -0700 (PDT) Date: Sun, 28 May 2023 02:29:02 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: Liang Chen , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, xuanzhuo@linux.alibaba.com, kuba@kernel.org, edumazet@google.com, davem@davemloft.net, pabeni@redhat.com, alexander.duyck@gmail.com Subject: Re: [PATCH net-next 1/5] virtio_net: Fix an unsafe reference to the page chain Message-ID: <20230528022737-mutt-send-email-mst@kernel.org> References: <20230526054621.18371-1-liangchen.linux@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 26, 2023 at 02:38:54PM +0800, Jason Wang wrote: > On Fri, May 26, 2023 at 1:46 PM Liang Chen wrote: > > > > "private" of buffer page is currently used for big mode to chain pages. > > But in mergeable mode, that offset of page could mean something else, > > e.g. when page_pool page is used instead. So excluding mergeable mode to > > avoid such a problem. > > If this issue happens only in the case of page_pool, it would be > better to squash it there. > > Thanks This is a tiny patch so I don't care. Generally it's ok to first rework code then change functionality. in this case what Jason says os right especially because you then do not need to explain that current code is ok. > > > > Signed-off-by: Liang Chen > > --- > > drivers/net/virtio_net.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index 5a7f7a76b920..c5dca0d92e64 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -497,7 +497,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, > > return NULL; > > > > page = (struct page *)page->private; > > - if (page) > > + if (!vi->mergeable_rx_bufs && page) > > give_pages(rq, page); > > goto ok; > > } > > -- > > 2.31.1 > >