From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f41.google.com (mail-ed1-f41.google.com [209.85.208.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 10F3C2917 for ; Mon, 4 Apr 2022 11:25:42 +0000 (UTC) Received: by mail-ed1-f41.google.com with SMTP id r10so4927904eda.1 for ; Mon, 04 Apr 2022 04:25:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=kRmmpGstRclPRjjwApH1btPXZBsTnruSxfck3SJh4r4=; b=Xec7SSTSA/UEqaC37ZEV4dE2Je2KNXkyivlAGkRdaKgATwXD69qOpLf58kgR/8LQ4V uXzPpwLF8ZCdagzQg/l468z1zBiUWzpsQikn5wDX2B8ZKGFWIAvBsVFvz7giqowIH5mN yOyMQOzWEEg8cliXz9FGxGVHLZhT1rEqe7cb7WR/xjFrJAUKOxZBokuGQ4ADmQRi5jtE TMWfeCZ0VCU/unt62Gwl15i9uwLRag8PYBX2hVkwtYO3HnpcO4tF4ziRLeodjADwM6be WSA0zRh9Kb9thwu+RaV4OfGEPvKMmmAV/tryX/b3AZk0U/xw6gdxHqmWUFO+Cl6rm2rJ oqjA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=kRmmpGstRclPRjjwApH1btPXZBsTnruSxfck3SJh4r4=; b=FECCiQHRU//FYbQGB5mnTeaPZLL8CIbzOz+sMBerluRfLqXVnTF/GaEEHpzyu9gSSK 157t38pYtNsnWvAmn/YWNfMDvnCNeRd7dN94liTipRktBRbfZCs0X1i1CqJdThyQbKdj pqT1mRqsMDm/yswToW51tma0a5Z+BiJd+7c8cBigRd6EsTnZKzgRSeoHiP3MJoYN4I+p JCLi7+7ElsS3nNxrGhuNEzmBdHjc9TRH+eCmhqnx9zJuXoLdWE6v1IXpXCV7pRDBt0Kr xdR+Co8XaXq0+OW+S7uaCYI5JDH52aO2BNMfhexcqnGFwdCAO9VzSnFZRce2yux++3Vk vUTA== X-Gm-Message-State: AOAM533lsPMt+ZUZHNrUf1hD8WK5+7EvWjmJloQ3qOdGwfsAhwEqDgYm NEdVrF94Ca4vlgCA01v0qcA= X-Google-Smtp-Source: ABdhPJyY3xQ7CifiD/LgTezse8vbp1FB/R+rACwG3s749AvUaz1JgbEKsxPat98dgdaYzyGXex/3Tg== X-Received: by 2002:a05:6402:f16:b0:419:d9f3:f8b with SMTP id i22-20020a0564020f1600b00419d9f30f8bmr32808680eda.33.1649071540223; Mon, 04 Apr 2022 04:25:40 -0700 (PDT) Received: from leap.localnet (host-95-249-145-232.retail.telecomitalia.it. [95.249.145.232]) by smtp.gmail.com with ESMTPSA id b3-20020aa7d483000000b00419209d4c85sm5076057edr.66.2022.04.04.04.25.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Apr 2022 04:25:39 -0700 (PDT) From: "Fabio M. De Francesco" To: Charlie Sands , Dan Carpenter Cc: gregkh@linuxfoundation.org, Larry.Finger@lwfinger.net, phil@philpotter.co.uk, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, paskripkin@gmail.com Subject: Re: [PATCH V2] Fix unsafe memory access by memcmp Date: Mon, 04 Apr 2022 13:25:37 +0200 Message-ID: <4729027.31r3eYUQgx@leap> In-Reply-To: <20220404105041.GX3293@kadam> References: <20220404105041.GX3293@kadam> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" On luned? 4 aprile 2022 12:50:41 CEST Dan Carpenter wrote: > On Sun, Apr 03, 2022 at 10:52:07PM -0400, Charlie Sands wrote: > > This patch fixes sparse warnings about the memcmp function unsafely > > accessing userspace memory without first copying it to kernel space. > > > > Signed-off-by: Charlie Sands > > --- > > > > V2: Fixed checkpatch.pl warning and changed variable name as suggested > > by Greg K. H. and improved error checking on the "copy_from_user" function as > > suggested by Pavel Skripkin. > > > > drivers/staging/r8188eu/os_dep/ioctl_linux.c | 21 ++++++++++++-------- > > 1 file changed, 13 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/staging/r8188eu/os_dep/ioctl_linux.c b/drivers/staging/r8188eu/os_dep/ioctl_linux.c > > index 7df213856d66..4b4eec2bde96 100644 > > --- a/drivers/staging/r8188eu/os_dep/ioctl_linux.c > > +++ b/drivers/staging/r8188eu/os_dep/ioctl_linux.c > > @@ -3233,23 +3233,28 @@ static int rtw_p2p_get(struct net_device *dev, > > struct iw_request_info *info, > > union iwreq_data *wrqu, char *extra) > > { > > - if (!memcmp(wrqu->data.pointer, "status", 6)) { > > + char wrqu_data[9]; > > + > > + if (copy_from_user(wrqu_data, wrqu->data.pointer, 9) != 0) > > + return 0; > > return -EFAULT; We can't assume that that user wants to copy 9 bytes > especially when they're passing a 4 character + NUL string. > > This is a custom ioctl. Called from ioctl_private_iw_point(). > > I think if you try to dereference a user pointer like this then it will > cause a crash, right? So that means no one has ever tested or used this > code and we hopefully we can just delete it? After a quick look, I'm pretty confident that we can also delete rtw_p2p_get2() and rtw_p2p_set() unless I'm overlooking something. Thanks, Fabio M. De Francesco