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 ECFA23CEBBD; Tue, 16 Jun 2026 18:20:11 +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=1781634013; cv=none; b=a6FbqnqvtDv9RuWizQxxCniw0INlztenPtlirR+f5FpnxDbHvJfYU3xxHsemhaV15AV9gOYDLXofDC5GWOSF5+B2i99ScEy7cA6pP5gQOjT4ssilQc0rQOO3gOMViNZWxOrsV0Tx4j+izOTe3aqOjKtKOtaiH6GXZxpsp3/3+jI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781634013; c=relaxed/simple; bh=HB6tSEhyo+TSqad4x2ZFl5Wmqw5zyGw9oTP93ggtI1Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fEkWIedZvnf545xwmt9xNzBPnwldtHG4HEeQB7CBZGqBxnpB9tBXv/OSvrNJ8sgppl02y8DZinpNiQx1krHlC6c20F+LSlBvGOqYaNDFd2miHmMvaygL0/4kR3FxpwuYQ8zujBGHCtz9t1dHFsVp4SU9XflshugG6huMajbax9M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=H7JhWAnO; 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="H7JhWAnO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD3871F000E9; Tue, 16 Jun 2026 18:20:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781634011; bh=b3wVfaVsq6/iCYIz5R/CKbSz5oB3UbxBjZs8LsvgUdg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=H7JhWAnOL8HeToow2jNUJokovO7UFj6B+I135UMFJyA0AdTB3IstO0hCWwvxZ3/XY eFHeTXKiAbgt5Y0bRHXNOx2VEHaRBYfi76D/fYEyJHLmrUqhwv6Ggbig8N54GpS/t6 KARaUTBvOMpc44J7312yea6Ea0HotKef4zUbGOXg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mingyu Wang <25181214217@stu.xidian.edu.cn>, Simon Horman , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 184/411] net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove Date: Tue, 16 Jun 2026 20:27:02 +0530 Message-ID: <20260616145110.479511279@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145100.376842714@linuxfoundation.org> References: <20260616145100.376842714@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: Mingyu Wang <25181214217@stu.xidian.edu.cn> [ Upstream commit a2171131ecda1ed61a594a1eb715e75fdad0fef5 ] In qrtr_port_remove(), the socket reference count is decremented via __sock_put() before the port is removed from the qrtr_ports XArray and before the RCU grace period elapses. This breaks the fundamental RCU update paradigm. It exposes a race window where a concurrent RCU reader (such as qrtr_reset_ports() or qrtr_port_lookup()) can obtain a pointer to the socket from the XArray, and attempt to call sock_hold() on a socket whose reference count has already dropped to zero. This exact race condition was hit during syzkaller fuzzing, leading to the following refcount saturation warning and a potential Use-After-Free: refcount_t: saturated; leaking memory. WARNING: CPU: 3 PID: 1273 at lib/refcount.c:22 refcount_warn_saturate+0xae/0x1d0 Modules linked in: qrtr(+) bochs drm_shmem_helper ... Call Trace: qrtr_reset_ports net/qrtr/af_qrtr.c:768 [inline] [qrtr] __qrtr_bind.isra.0+0x48b/0x570 net/qrtr/af_qrtr.c:805 [qrtr] qrtr_bind+0x17d/0x210 net/qrtr/af_qrtr.c:901 [qrtr] kernel_bind+0xe4/0x120 net/socket.c:3592 qrtr_ns_init+0x1a6/0x380 net/qrtr/ns.c:715 [qrtr] qrtr_proto_init+0x3b/0xff0 net/qrtr/af_qrtr.c:169 [qrtr] do_one_initcall+0xf5/0x5e0 init/main.c:1283 ... Fix this by deferring the reference count decrement until after the xa_erase() and the synchronize_rcu() complete. (Note: The v1 of this patch incorrectly replaced __sock_put() with sock_put(). As Simon Horman pointed out, the callers of qrtr_port_remove() still hold a reference to the socket, so freeing the socket memory here would lead to a subsequent UAF in the caller. Thus, the __sock_put() is kept, but only repositioned to close the RCU race.) Fixes: bdabad3e363d ("net: Add Qualcomm IPC router") Signed-off-by: Mingyu Wang <25181214217@stu.xidian.edu.cn> Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260604064801.1180388-1-w15303746062@163.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/qrtr/af_qrtr.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/qrtr/af_qrtr.c b/net/qrtr/af_qrtr.c index 431fd1f2b80c18..6f4b901afc330c 100644 --- a/net/qrtr/af_qrtr.c +++ b/net/qrtr/af_qrtr.c @@ -702,13 +702,13 @@ static void qrtr_port_remove(struct qrtr_sock *ipc) if (port == QRTR_PORT_CTRL) port = 0; - __sock_put(&ipc->sk); - xa_erase(&qrtr_ports, port); /* Ensure that if qrtr_port_lookup() did enter the RCU read section we * wait for it to up increment the refcount */ synchronize_rcu(); + + __sock_put(&ipc->sk); } /* Assign port number to socket. -- 2.53.0