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(unknown [2a02:6bf:8080:748::1:e]) by mail-nwsmtp-smtp-corp-main-69.vla.yp-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id tSGfVF0GwiE0-9xcylu02; Wed, 16 Jul 2025 10:28:56 +0300 X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1752650936; bh=tevAFdVUBjnHSaFGZQIwdDr3jmIGLGbxnsXQaNZ76+I=; h=Message-ID:Date:Cc:Subject:To:From; b=s+hNaCK4KmcEvLgkOzyqlArTlDoZl2+dXXdBIgsiiMjxI9dHXnSVuiD1LLwQufQhK T9QAtEazGztMvBgH1NMlcHkJLhfmgHJOLFfKvwvgd/q9STxlDy9RN0amlPVq1tTSbS OW7ZHcEqR1PHejf1n3UuFpdS+nsKtzkHszWKAWr8= Authentication-Results: mail-nwsmtp-smtp-corp-main-69.vla.yp-c.yandex.net; dkim=pass header.i=@yandex-team.ru From: Vladimir Sementsov-Ogievskiy To: qemu-devel@nongnu.org, jasowang@redhat.com Cc: vsementsov@yandex-team.ru, d-tatianin@yandex-team.ru, leiyang@redhat.com Subject: [PATCH v2] net/tap: drop too small packets Date: Wed, 16 Jul 2025 10:28:53 +0300 Message-ID: <20250716072854.13403-1-vsementsov@yandex-team.ru> X-Mailer: git-send-email 2.48.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a02:6b8:c0e:500:1:45:d181:df01; envelope-from=vsementsov@yandex-team.ru; helo=forwardcorp1a.mail.yandex.net X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @yandex-team.ru) X-ZM-MESSAGEID: 1752650982045116600 Content-Type: text/plain; charset="utf-8" Theoretically tap_read_packet() may return size less than s->host_vnet_hdr_len, and next, we'll work with negative size (in case of !s->using_vnet_hdr). Let's avoid it. Don't proceed with size =3D=3D s->host_vnet_hdr_len as well in case of !s->using_vnet_hdr, it doesn't make sense. Signed-off-by: Vladimir Sementsov-Ogievskiy Tested-by: Lei Yang --- v2: change "<" -> "<=3D" net/tap.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/tap.c b/net/tap.c index 23536c09b46..2a859360193 100644 --- a/net/tap.c +++ b/net/tap.c @@ -190,6 +190,11 @@ static void tap_send(void *opaque) break; } =20 + if (s->host_vnet_hdr_len && size <=3D s->host_vnet_hdr_len) { + /* Invalid packet */ + break; + } + if (s->host_vnet_hdr_len && !s->using_vnet_hdr) { buf +=3D s->host_vnet_hdr_len; size -=3D s->host_vnet_hdr_len; --=20 2.48.1