From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9D9DB2E62B7; Tue, 17 Mar 2026 16:50:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773766203; cv=none; b=Ba0RX9iei96ewEm2wYL8wC3pv58RGjStZusLON2aWf5CqF7EF5Opdphpg2nilIF4Fp+DR6nFzmHx8K/U2WG9AsRuFKYK8OBdfHTihnz7VK8cp3IdoS7fJ7ysZjz/nWjXDM/QxuHmksQ/IwtRPLZtMBq3eH99goBh5LOGR2+KXLw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773766203; c=relaxed/simple; bh=/o240w/Gg2XkCQX7I1IH+ff9ScN9/g6wm6cDCSjE+no=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RKs4m4XAy+FloHoo4zPt/FxxUVj22O/JwZkJTVr0U8imMCmssfDP+aGKLWk65CE8rVHX0RXebUr9iCCgUfQ3IpxHRqebEhVk/FjwGjJgdqaBcMluA2PagkvM03HntMctbYGmMbUsWaI/U1Fjw8ioIgGIQmD2cOMVgb/GZe+rkGk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0DxUEF3J; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0DxUEF3J" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F16F9C4CEF7; Tue, 17 Mar 2026 16:50:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1773766203; bh=/o240w/Gg2XkCQX7I1IH+ff9ScN9/g6wm6cDCSjE+no=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0DxUEF3J14rMArMsimhIkqd8PlzgbT8BbiHRb4pm1af3jneR/pGOVSEfGGcyzNyYt jMWkwpOZXllg06lqaYkaN1doF2tjhSLRMxRMmDd58/aBqEqFl0ebwphY8CQmHTnHp4 +n8arlrqfC/O1NTnlbL4zDuU23BWxSqxV34RrY/A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, Kuen-Han Tsai Subject: [PATCH 6.19 165/378] usb: gadget: f_ncm: Fix atomic context locking issue Date: Tue, 17 Mar 2026 17:32:02 +0100 Message-ID: <20260317163013.081156128@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260317163006.959177102@linuxfoundation.org> References: <20260317163006.959177102@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuen-Han Tsai commit 0d6c8144ca4d93253de952a5ea0028c19ed7ab68 upstream. The ncm_set_alt function was holding a mutex to protect against races with configfs, which invokes the might-sleep function inside an atomic context. Remove the struct net_device pointer from the f_ncm_opts structure to eliminate the contention. The connection state is now managed by a new boolean flag to preserve the use-after-free fix from commit 6334b8e4553c ("usb: gadget: f_ncm: Fix UAF ncm object at re-bind after usb ep transport error"). BUG: sleeping function called from invalid context Call Trace: dump_stack_lvl+0x83/0xc0 dump_stack+0x14/0x16 __might_resched+0x389/0x4c0 __might_sleep+0x8e/0x100 ... __mutex_lock+0x6f/0x1740 ... ncm_set_alt+0x209/0xa40 set_config+0x6b6/0xb40 composite_setup+0x734/0x2b40 ... Fixes: 56a512a9b410 ("usb: gadget: f_ncm: align net_device lifecycle with bind/unbind") Cc: stable@kernel.org Signed-off-by: Kuen-Han Tsai Link: https://patch.msgid.link/20260221-legacy-ncm-v2-2-dfb891d76507@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_ncm.c | 29 ++++++++++--------------- drivers/usb/gadget/function/u_ether_configfs.h | 11 --------- drivers/usb/gadget/function/u_ncm.h | 1 3 files changed, 13 insertions(+), 28 deletions(-) --- a/drivers/usb/gadget/function/f_ncm.c +++ b/drivers/usb/gadget/function/f_ncm.c @@ -58,6 +58,7 @@ struct f_ncm { u8 notify_state; atomic_t notify_count; bool is_open; + bool is_connected; const struct ndp_parser_opts *parser_opts; bool is_crc; @@ -864,7 +865,6 @@ invalid: static int ncm_set_alt(struct usb_function *f, unsigned intf, unsigned alt) { struct f_ncm *ncm = func_to_ncm(f); - struct f_ncm_opts *opts = func_to_ncm_opts(f); struct usb_composite_dev *cdev = f->config->cdev; /* Control interface has only altsetting 0 */ @@ -887,13 +887,12 @@ static int ncm_set_alt(struct usb_functi if (alt > 1) goto fail; - scoped_guard(mutex, &opts->lock) - if (opts->net) { - DBG(cdev, "reset ncm\n"); - opts->net = NULL; - gether_disconnect(&ncm->port); - ncm_reset_values(ncm); - } + if (ncm->is_connected) { + DBG(cdev, "reset ncm\n"); + ncm->is_connected = false; + gether_disconnect(&ncm->port); + ncm_reset_values(ncm); + } /* * CDC Network only sends data in non-default altsettings. @@ -926,8 +925,7 @@ static int ncm_set_alt(struct usb_functi net = gether_connect(&ncm->port); if (IS_ERR(net)) return PTR_ERR(net); - scoped_guard(mutex, &opts->lock) - opts->net = net; + ncm->is_connected = true; } spin_lock(&ncm->lock); @@ -1374,16 +1372,14 @@ err: static void ncm_disable(struct usb_function *f) { struct f_ncm *ncm = func_to_ncm(f); - struct f_ncm_opts *opts = func_to_ncm_opts(f); struct usb_composite_dev *cdev = f->config->cdev; DBG(cdev, "ncm deactivated\n"); - scoped_guard(mutex, &opts->lock) - if (opts->net) { - opts->net = NULL; - gether_disconnect(&ncm->port); - } + if (ncm->is_connected) { + ncm->is_connected = false; + gether_disconnect(&ncm->port); + } if (ncm->notify->enabled) { usb_ep_disable(ncm->notify); @@ -1687,7 +1683,6 @@ static struct usb_function_instance *ncm if (!opts) return ERR_PTR(-ENOMEM); - opts->net = NULL; opts->ncm_os_desc.ext_compat_id = opts->ncm_ext_compat_id; gether_setup_opts_default(&opts->net_opts, "usb"); --- a/drivers/usb/gadget/function/u_ether_configfs.h +++ b/drivers/usb/gadget/function/u_ether_configfs.h @@ -326,18 +326,9 @@ out: \ char *page) \ { \ struct f_##_f_##_opts *opts = to_f_##_f_##_opts(item); \ - const char *name; \ \ guard(mutex)(&opts->lock); \ - rtnl_lock(); \ - if (opts->net_opts.ifname_set) \ - name = opts->net_opts.name; \ - else if (opts->net) \ - name = netdev_name(opts->net); \ - else \ - name = "(inactive net_device)"; \ - rtnl_unlock(); \ - return sysfs_emit(page, "%s\n", name); \ + return sysfs_emit(page, "%s\n", opts->net_opts.name); \ } \ \ static ssize_t _f_##_opts_ifname_store(struct config_item *item, \ --- a/drivers/usb/gadget/function/u_ncm.h +++ b/drivers/usb/gadget/function/u_ncm.h @@ -19,7 +19,6 @@ struct f_ncm_opts { struct usb_function_instance func_inst; - struct net_device *net; struct gether_opts net_opts; struct config_group *ncm_interf_group;