[{"id":3676534,"web_url":"http://patchwork.ozlabs.org/comment/3676534/","msgid":"","list_archive_url":null,"date":"2026-04-13T08:08:47","subject":"Re: [PATCH 3/5] staging: nvec: fix use-after-free in\n nvec_rx_completed()","submitter":{"id":389,"url":"http://patchwork.ozlabs.org/api/people/389/","name":"Dan Carpenter","email":"error27@gmail.com"},"content":"On Sun, Apr 12, 2026 at 10:51:16PM +0200, Alexandru Hossu wrote:\n> In nvec_rx_completed(), when an incomplete RX transfer is detected,\n> nvec_msg_free() is called to return the message back to the pool by\n> clearing its 'used' atomic flag. Immediately after this, the code\n> accesses nvec->rx->data[0] to check the message type.\n> \n> Since nvec_msg_free() marks the pool slot as available via atomic_set(),\n> any concurrent or subsequent call to nvec_msg_alloc() could claim that\n> same slot and overwrite its data[] array. Reading nvec->rx->data[0] after\n> freeing the message is therefore a use-after-free.\n> \n> Fix this by saving the message type byte before calling nvec_msg_free(),\n> then using the saved value for the battery quirk check.\n> \n> Signed-off-by: Alexandru Hossu \n\nAdd a Fixes tag.\n\n> ---\n> drivers/staging/nvec/nvec.c | 5 ++++-\n> 1 file changed, 4 insertions(+), 1 deletion(-)\n> \n> diff --git a/drivers/staging/nvec/nvec.c b/drivers/staging/nvec/nvec.c\n> index 952c5a849a56..75877038847f 100644\n> --- a/drivers/staging/nvec/nvec.c\n> +++ b/drivers/staging/nvec/nvec.c\n> @@ -498,11 +498,14 @@ static void nvec_rx_completed(struct nvec_chip *nvec)\n> \t\t\t(uint)nvec_msg_size(nvec->rx),\n> \t\t\t(uint)nvec->rx->pos);\n> \n> +\t\t/* Save before freeing to avoid use-after-free */\n\nDelete this comment. (Obvious).\n\n> +\t\tunsigned char msg_type = nvec->rx->data[0];\n\nMove this declaration to the start of the block.\n\nOtherwise, it looks good.\n\nregards,\ndan carpenter\n\n> +\n> \t\tnvec_msg_free(nvec, nvec->rx);\n> \t\tnvec->state = 0;\n> \n> \t\t/* Battery quirk - Often incomplete, and likes to crash */\n> -\t\tif (nvec->rx->data[0] == NVEC_BAT)\n> +\t\tif (msg_type == NVEC_BAT)\n> \t\t\tcomplete(&nvec->ec_transfer);\n> \n> \t\treturn;","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-tegra@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=ebu2IRcz;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; helo=tor.lore.kernel.org;\n envelope-from=linux-tegra+bounces-13737-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)","smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com\n header.b=\"ebu2IRcz\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=209.85.128.48","smtp.subspace.kernel.org;\n dmarc=pass (p=none dis=none) header.from=gmail.com","smtp.subspace.kernel.org;\n spf=pass smtp.mailfrom=gmail.com"],"Received":["from tor.lore.kernel.org (tor.lore.kernel.org\n [IPv6:2600:3c04:e001:36c::12fc:5321])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fvKp35449z1xtJ\n\tfor ; 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