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 8F8AB50EC15; Wed, 30 Sep 2026 18:01:32 +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=1790791293; cv=none; b=fimTeIWxePOTOnA/AZiVm/3uyo/r28YcMjO9tGWa8UiAxdLKe4jehcGKDqYxBn2eKP6El+5d/PxLD5GFfobLn+DZHYD9WktyBvNYzpYGYDCD/nM6CIt2cduVPDbfjhK6uaJGl5KxCk87IpWLD82yxD3oJRrRrLMi6MgJ1apFURs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791293; c=relaxed/simple; bh=1ucMqCNG7m+Fh/ldo7ph2ByA49S5MGE98rscqiF1i/E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CKY+aYhnIn2WQSOrTCvUmJfeMJJPxNpXUPbmQ0P9OR2xfR5ESx7pCr+NPmGODac4x2VFOOEksM+0b8Ua6fMCso/5y5kohvxDTTUaCfXztB0fo7IlWdVy5jyEmq/FE5MnIL/dpFuhbeyfJupD5ifdJb54QQgzYTS1yLMKmctYW9I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bsumf5rq; 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="bsumf5rq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1E3B1F00898; Wed, 30 Sep 2026 18:01:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790791292; bh=b/Y2er3/J4CaTrMxalNOKxU4BhKOTUAIRzRjnBp3lHg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bsumf5rqhaZnog7JVJ7TM2ECJwVX77b1A9xGShhscxTpYESVS7W9oNjh4gxJz9Vy7 MW2Co5qUi0TSrZzQTL4QaoG5wRUeZaOA/F0cVCsxnED41F6zxYRzHrLyer+mCu8Ty4 cgF7JmxUjBy1oG9OcO3Vp8nTrH6KN47Ys1A6eGps= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jiale Yao , Luiz Augusto von Dentz , Sasha Levin Subject: [PATCH 5.15 224/752] Bluetooth: RFCOMM: validate skb length in rfcomm_recv_frame Date: Wed, 30 Sep 2026 17:21:34 +0200 Message-ID: <20260930152403.102566661@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: Jiale Yao [ Upstream commit b230e5bf501c5edaf2eb0991cb862ac142031d4b ] rfcomm_recv_frame() casts skb->data to struct rfcomm_hdr and dereferences hdr->addr and hdr->ctrl without validating skb->len first. A truncated frame with skb->len less than the minimum header size causes an out-of-bounds read of uninitialized memory. Additionally, a zero-length frame causes skb->len-- to underflow to UINT_MAX, making skb_tail_pointer() read far past the buffer. Commit 23882b828c3c ("Bluetooth: RFCOMM: validate skb length in MCC handlers") fixed the same class of missing-length-check bugs in the MCC sub-handlers, but the top-level rfcomm_recv_frame() was left unfixed. KMSAN reports: BUG: KMSAN: uninit-value in rfcomm_run ... Uninit was created at: __alloc_skb+0x474/0xb60 vhci_write+0xe9/0x870 Fix this by rejecting frames smaller than sizeof(struct rfcomm_hdr) + 1 (the minimum frame must have a 3-byte header and a 1-byte FCS). Signed-off-by: Jiale Yao Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- net/bluetooth/rfcomm/core.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c index 2914ac1c50024..104d75908dbc9 100644 --- a/net/bluetooth/rfcomm/core.c +++ b/net/bluetooth/rfcomm/core.c @@ -1813,6 +1813,11 @@ static struct rfcomm_session *rfcomm_recv_frame(struct rfcomm_session *s, return s; } + if (skb->len < sizeof(*hdr) + 1) { + kfree_skb(skb); + return s; + } + dlci = __get_dlci(hdr->addr); type = __get_type(hdr->ctrl); -- 2.53.0