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 83E1F2E282B; Thu, 17 Sep 2026 17:09:44 +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=1789664985; cv=none; b=pB0ng9j87YTkBIXddtR5Q49zthhmIpDSOCthQLeXXxOt8IiAqg1gUh5EkRfF/SLkpsJ65+z3OETuLjtizFvXGkQNr71bCFXoF98OhQ63kK1ESpuiSK2T+a7rS7hd5TZ7fl3WI4OcRx2L0fe5AGBMPZBL9AXjqLGx0+LrNI1CopI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789664985; c=relaxed/simple; bh=ewKG9WwYz8JR3jSi3X6Gzj+zKV0vOHmnDqAZehNCpQo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ihGXXF4PFkw+l15FGC618WFwSNto/ZvAEaeG2kVQmeqcKfM3eW6svWkgNhf6AUW1VXuXiu0E679UvoFXy70Li86dk6A0/eYCFJOpCZKXwR/W2XsYltUJY/7B+RBhaJsOXkbetNCpAy5/Gzh1496dAxKIeaeCA0NUgk3y1gvbQyM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ucy7aWs9; 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="ucy7aWs9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DB9C41F0089A; Thu, 17 Sep 2026 17:09:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789664984; bh=Vx9BPypgLYHLYvELhEQqIC5+HxHjG+2nKf73sa/vqHc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ucy7aWs9pIFWhY6hDlR9U5GRBYZbAh3UOTCtPcaplnKYw/8dgvgqoRU5BUhQb304w 31YIrlzumF5CULl5mH3xn2EeZilkUGvvyBno/6YG0+Uph33x5bTTmHSHbjtrFwhCO9 I2HPxSBW+oSv1iqn254Pu5OmTEx7BT+C3q1Mmz7E= 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 6.18 0552/1250] Bluetooth: RFCOMM: validate skb length in rfcomm_recv_frame Date: Thu, 17 Sep 2026 16:05:47 +0100 Message-ID: <20260917151606.895520710@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151551.901433442@linuxfoundation.org> References: <20260917151551.901433442@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 6.18-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 6571b33d553ea..45f8cfebcc6a6 100644 --- a/net/bluetooth/rfcomm/core.c +++ b/net/bluetooth/rfcomm/core.c @@ -1817,6 +1817,11 @@ 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