From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7466E511E90; Wed, 30 Sep 2026 18:19:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790792382; cv=none; b=HJuW9HvWLj1yvXnwKlSV0Rx/5mexR0rgJ53HAN1aDPi5DXvaH84o1i32AbxxNCqm0SWLN0iUO0Xgip3iBUIupAIWSafH5sUwwCr9UBJxIQqnnnN758WzvmQSbke67fpt8v1+WttvM2yvPgIovHFPqgw+7eFrBwSE4o3Z/P5jBnA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790792382; c=relaxed/simple; bh=CM3WwAlOp1pQY5fgDrks/KH8dH7RhIkNxkVF0gljDlk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Psp8He+HpkDchj142lboruM9bYTfru20HD5ySUsVR2cIxAPDFh/sG3MHRMHTAvmKZowqrrwEmWp/Wd7ha1LSbvUUiBC1D6ZApWe5RQtiMRZYeYEca2720yFTVq/QpU6s9rP4Qli9OZtjpEgN8fSmNSs8uoKFmB2O8LDiEHgQ3xY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=UODVKiRD; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="UODVKiRD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF1F51F000FF; Wed, 30 Sep 2026 18:19:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790792381; bh=JSK7YpPIB/GFEfPQznXA3B4s+dY5QhBlliEzmCxJxS8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UODVKiRDb4oSoCwctj7YsMw/Nu5YRtYxEr6XWoO7UtB2gz9CHgqKRoxvSCCO48co1 VN1OvYS4oaV9b+lI52CVDPY77FkAPuc3pux4Uxwy1vm6+bd7y6wBtmsJeBBA9IbVh/ w9YFodSLdWr0cXysdzKq9J8A4+7FETzxshL5GPeU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hui Peng , Luiz Augusto von Dentz , Sasha Levin Subject: [PATCH 5.15 634/752] Bluetooth: RFCOMM: Reject short EA=0 frames in rfcomm_recv_frame() Date: Wed, 30 Sep 2026 17:28:24 +0200 Message-ID: <20260930152411.988975897@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hui Peng [ Upstream commit 6d91041bb38b97e2feb625123cc0529d7b83a0e1 ] While rfcomm_recv_frame() verifies that skb->len is at least sizeof(*hdr) + 1 (4 bytes: 3-byte header + 1-byte FCS), an RFCOMM frame with an extended 2-byte length field (!__test_ea(hdr->len)) has a 4-byte header plus a 1-byte FCS (5 bytes minimum, sizeof(*hdr) + 2). When a 4-byte RFCOMM frame with EA == 0 arrives: 1. The initial skb->len < sizeof(*hdr) + 1 check passes (4 < 4 is false). 2. Trimming the FCS byte decrements skb->len to 3. 3. If __check_fcs() succeeds, skb_pull(skb, 4) fails (4 > 3) and returns NULL without advancing skb->data. 4. Because the return value of skb_pull() is ignored, the un-pulled 3-byte struct rfcomm_hdr remains at skb->data and is either queued as application payload via rfcomm_recv_data() or parsed as a multiplexer control command via rfcomm_recv_mcc() on DLCI 0. Fix this by extending the length check in rfcomm_recv_frame() to also require skb->len >= sizeof(*hdr) + 2 when !__test_ea(hdr->len). Fixes: b230e5bf501c ("Bluetooth: RFCOMM: validate skb length in rfcomm_recv_frame") Assisted-by: LLM Signed-off-by: Hui Peng Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- net/bluetooth/rfcomm/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c index 104d75908dbc9..6324e03ff0d07 100644 --- a/net/bluetooth/rfcomm/core.c +++ b/net/bluetooth/rfcomm/core.c @@ -1813,7 +1813,8 @@ static struct rfcomm_session *rfcomm_recv_frame(struct rfcomm_session *s, return s; } - if (skb->len < sizeof(*hdr) + 1) { + if (skb->len < sizeof(*hdr) + 1 || + (!__test_ea(hdr->len) && skb->len < sizeof(*hdr) + 2)) { kfree_skb(skb); return s; } -- 2.53.0