From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Mon, 20 Nov 2023 14:34:11 +0100 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1r54Pj-001VkC-0A for lore@lore.pengutronix.de; Mon, 20 Nov 2023 14:34:11 +0100 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1r54Pj-0001oG-1D for lore@pengutronix.de; Mon, 20 Nov 2023 14:34:11 +0100 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From :Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Re/VZekaqD+kGVQ5eBe0Ni2aG5evW4P5ow6dUYHx6nI=; b=1AHV5I2bm03c17lN6VCmRF8JcN CHRvhYokVtJ1w/S4CLIwzMtFbYeJ7J8REFb9MTZ4PNXRVGpdy71MaOvVxcsDE8u0vQaptGJBQeo+a MCF7K0pAleLOiu6VDq0K1inEVJP60sqr/1VjyinMPIuuzKYSK9E1vKPsyJg6PM6z7lU1KGWphdGNC Hw4OT8qurqxHU6EhMQxVcZgXLdPvw2Ald4m/0bsN7SzOGe3xoI3286Cqzx3tlVo7doaYu/DQ+oLs7 DP4ipCA6uvvLkwXsqlKILfQoiBVuCT4VynHA8loYaukjiqK3Z/sDtJuJQqNkj/B4AeW92weQ5dSSg iknCAiaQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1r54Ny-00CA1S-0q; Mon, 20 Nov 2023 13:32:22 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1r54Nr-00C9zk-2w for barebox@lists.infradead.org; Mon, 20 Nov 2023 13:32:20 +0000 Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[127.0.0.1]) by metis.whiteo.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1r54Nk-0001OC-Cd for barebox@lists.infradead.org; Mon, 20 Nov 2023 14:32:08 +0100 Message-ID: Date: Mon, 20 Nov 2023 14:32:08 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Content-Language: en-US To: "barebox@lists.infradead.org" References: <20231120083750.3967831-1-a.fatoum@pengutronix.de> From: Ahmad Fatoum In-Reply-To: <20231120083750.3967831-1-a.fatoum@pengutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231120_053215_969196_4845C434 X-CRM114-Status: GOOD ( 23.93 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-7.0 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH RFC 1/3] fs: add open O_TMPFILE support X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) On 20.11.23 09:37, Ahmad Fatoum wrote: > barebox dentry cache is never cleared with the assumption that there > should be enough RAM anyway to cache all lookups until boot. > > When fuzzing barebox however, there is no limit to how many dentries > are added to the cache. This is e.g. problematic when fuzzing the FIT > parser: FIT images can have compressed payloads. Compressed payloads are > passed to uncompress_buf_to_buf, which uses a new random file in ramfs > as destination. A fuzzer would thus create a dentry for every iteration, > rapidly depleting memory. > > A general solution for that would be dropping the dentry cache on memory > pressure. In the special case of uncompress_buf_to_buf, it would already > be enough though to sidestep the dentry cache and create an anonymous > file. Linux provides this with the O_TMPFILE option, so let's add the > equivalent to barebox. > > Signed-off-by: Ahmad Fatoum > --- > fs/fs.c | 29 +++++++++++++++++++++++++++++ > include/fcntl.h | 3 +++ > 2 files changed, 32 insertions(+) > > diff --git a/fs/fs.c b/fs/fs.c > index 1800d6826ddc..6bd3c2df3c31 100644 > --- a/fs/fs.c > +++ b/fs/fs.c > @@ -2539,6 +2539,35 @@ int open(const char *pathname, int flags, ...) > const char *s; > struct filename *filename; > > + if (flags & O_TMPFILE) { > + fsdev = get_fsdevice_by_path(pathname); > + if (!fsdev) { > + errno = ENOENT; > + return -errno; > + } > + > + if (fsdrv != ramfs_driver) { > + errno = EOPNOTSUPP; > + return -errno; > + } Ouch should be fsdev->driver. Will retest and resend. > + > + f = get_file(); > + if (!f) { > + errno = EMFILE; > + return -errno; > + } > + > + f->path = NULL; > + f->dentry = NULL; > + f->f_inode = new_inode(&fsdev->sb); > + f->f_inode->i_mode = S_IFREG; > + f->flags = flags; > + f->size = 0; > + f->fsdev = fsdev; > + > + return f->no; > + } > + > filename = getname(pathname); > if (IS_ERR(filename)) > return PTR_ERR(filename); > diff --git a/include/fcntl.h b/include/fcntl.h > index 2e7c0eed3479..1b4cd8ad3783 100644 > --- a/include/fcntl.h > +++ b/include/fcntl.h > @@ -16,6 +16,9 @@ > #define O_APPEND 00002000 > #define O_DIRECTORY 00200000 /* must be a directory */ > #define O_NOFOLLOW 00400000 /* don't follow links */ > +#define __O_TMPFILE 020000000 > + > +#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY) > > /* barebox additional flags */ > #define O_RWSIZE_MASK 017000000 -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |