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 8B763201278 for ; Sat, 11 Apr 2026 16:31:09 +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=1775925069; cv=none; b=E98EIVVf6TYBHtnn4lHHu/wm5tWNKXuneU+Yt8NTAKKc3cLnUaWDOcC37/DbUrarnp/j9FHB2+Ilt6GmnmRPQWJ47DVvTKuVvhN8PVDs0tuqxIVNsj1I5+UmuNDuxKr85h+gqiv97jFi7lQ7nuj+BxeKlGLvc1Eby2PpgNTp924= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775925069; c=relaxed/simple; bh=9TKfg99zWxZ8KtBnEXBAlnncc/gKvUzv2bMReYk4JjU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tABzinulqEc82R39dxTTvl7680iCkdnRWchq3XEGKqhtzWnYytnGgf0w0b+c6wktAEIin7LdSo07A46EF6GfkCTyC86WwiWPPKZbVGfLdRgyvRKy4HhJt7kx5Xk3MgpI3g8qJ8S22ypOHPnVgeinNjm5al98PI3QFKLSWDudL9s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M6hN8Q9N; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="M6hN8Q9N" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F515C4CEF7; Sat, 11 Apr 2026 16:31:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775925069; bh=9TKfg99zWxZ8KtBnEXBAlnncc/gKvUzv2bMReYk4JjU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=M6hN8Q9NBz053I/lEmTlxeCQ5MZeE5tk/4wZjF7v2t3sdf2oOjnQdXk1gXtpqFBN1 m2aPlG0OhVYFzyFexpSjSnUWhARSjwZ74ZyzS3mrtAp24Os+FiUzZvDbUwE1/mFTW1 YmU9avakRbsSp0Xd3ZG33w7HdMmERFXQixPSjob1GFmOL5eg/xldmh8s/9FFYHTW2Z 9JAE/uGOyAf22gdKrbKZdOAeQcaiaise2KjoACBvghFlcMNDZf1cY4NPJypuxajaWa 1XvTgd0wSfK5w747j4RD4bIB0qSGhws8L36iNo7fdqlhg1elyRqBPxDS0d5JIFFeUg ktjbJKJulo6ig== From: Sasha Levin To: stable@vger.kernel.org Cc: Kuen-Han Tsai , stable , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 5.15.y] usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop Date: Sat, 11 Apr 2026 12:31:06 -0400 Message-ID: <20260411163106.807249-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026040856-reunion-region-2d33@gregkh> References: <2026040856-reunion-region-2d33@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Kuen-Han Tsai [ Upstream commit e1eabb072c75681f78312c484ccfffb7430f206e ] A race condition between gether_disconnect() and eth_stop() leads to a NULL pointer dereference. Specifically, if eth_stop() is triggered concurrently while gether_disconnect() is tearing down the endpoints, eth_stop() attempts to access the cleared endpoint descriptor, causing the following NPE: Unable to handle kernel NULL pointer dereference Call trace: __dwc3_gadget_ep_enable+0x60/0x788 dwc3_gadget_ep_enable+0x70/0xe4 usb_ep_enable+0x60/0x15c eth_stop+0xb8/0x108 Because eth_stop() crashes while holding the dev->lock, the thread running gether_disconnect() fails to acquire the same lock and spins forever, resulting in a hardlockup: Core - Debugging Information for Hardlockup core(7) Call trace: queued_spin_lock_slowpath+0x94/0x488 _raw_spin_lock+0x64/0x6c gether_disconnect+0x19c/0x1e8 ncm_set_alt+0x68/0x1a0 composite_setup+0x6a0/0xc50 The root cause is that the clearing of dev->port_usb in gether_disconnect() is delayed until the end of the function. Move the clearing of dev->port_usb to the very beginning of gether_disconnect() while holding dev->lock. This cuts off the link immediately, ensuring eth_stop() will see dev->port_usb as NULL and safely bail out. Fixes: 2b3d942c4878 ("usb ethernet gadget: split out network core") Cc: stable Signed-off-by: Kuen-Han Tsai Link: https://patch.msgid.link/20260311-gether-disconnect-npe-v1-1-454966adf7c7@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/gadget/function/u_ether.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c index 116dbc2ae04dd..927064726c7a5 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -1173,6 +1173,10 @@ void gether_disconnect(struct gether *link) DBG(dev, "%s\n", __func__); + spin_lock(&dev->lock); + dev->port_usb = NULL; + spin_unlock(&dev->lock); + netif_stop_queue(dev->net); netif_carrier_off(dev->net); @@ -1210,10 +1214,6 @@ void gether_disconnect(struct gether *link) dev->header_len = 0; dev->unwrap = NULL; dev->wrap = NULL; - - spin_lock(&dev->lock); - dev->port_usb = NULL; - spin_unlock(&dev->lock); } EXPORT_SYMBOL_GPL(gether_disconnect); -- 2.53.0