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(unknown [2a02:6bf:8080:73d::1:28]) by mail-nwsmtp-smtp-corp-main-34.sas.yp-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id BtZDqQ0FieA0-fXzqSqxA; Thu, 03 Jul 2025 13:55:11 +0300 X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1751540111; bh=3Mrwbefvrcn1WEr6p5kBz3zCiVEFVKwBqtJ+4hKe6PU=; h=Message-ID:Date:Cc:Subject:To:From; b=FpHGA5VbnY1zhZOqIfo0CGk/VEw+PRDBBXq5kX/hpni+D3b2FytvRLTTavjns+oUj 8L1F4DHvLCBBXAmV9lDhZv0Mehfy85+W2quwB0xtlPT17HTO+5WMiFrjMEa3+Js4wf fY09r2t38vUfyaxVfbQNXoZvg2FZcr//dB7vYadI= Authentication-Results: mail-nwsmtp-smtp-corp-main-34.sas.yp-c.yandex.net; dkim=pass header.i=@yandex-team.ru From: Vladimir Sementsov-Ogievskiy To: jasowang@redhat.com Cc: qemu-devel@nongnu.org, vsementsov@yandex-team.ru, d-tatianin@yandex-team.ru Subject: [PATCH] net/tap: drop too small packets Date: Thu, 3 Jul 2025 13:55:08 +0300 Message-ID: <20250703105508.2380494-1-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:c02:900:1:45:d181:df01; envelope-from=vsementsov@yandex-team.ru; helo=forwardcorp1b.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, 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: 1751540145219116600 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. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Daniil Tatianin Tested-by: Lei Yang --- net/tap.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/tap.c b/net/tap.c index ae1c7e39832..20d0dc2eb35 100644 --- a/net/tap.c +++ b/net/tap.c @@ -172,6 +172,11 @@ static void tap_send(void *opaque) break; } =20 + if (s->host_vnet_hdr_len && size < 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