From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Tue, 08 Sep 2026 10:32:55 +0200 Received: from mx1.white.stw.pengutronix.de ([2a0a:edc0:0:b01:1d::107]) 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 1x3rGB-001TKo-2E for lore@lore.pengutronix.de; Tue, 08 Sep 2026 10:32:55 +0200 Authentication-Results: mx1.white.stw.pengutronix.de; dkim=pass header.d=lists.infradead.org header.s=bombadil.20210309 header.b=VyVls1gi; spf=pass (mx1.white.stw.pengutronix.de: domain of "barebox-bounces+lore=pengutronix.de@lists.infradead.org" designates 2607:7c80:54:3::133 as permitted sender) smtp.mailfrom="barebox-bounces+lore=pengutronix.de@lists.infradead.org"; dmarc=none Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by mx1.white.stw.pengutronix.de (Postfix) with ESMTPS id 7BCC8201CD1 for ; Tue, 08 Sep 2026 10:32:55 +0200 (CEST) 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:To:In-Reply-To:References: Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=PMahfrXlBVg35v/WuJgNwobOO9vjKDOSQMl64yZjAPs=; b=VyVls1gi85Pw9ywnBPmu2HqRF6 tTWgquqBbncYJ3QlfyF/i1qkpCAmCkaebu3AHZMk/v7Pe/tLLZcpFovPtSpSpaFyE7rOFTqNWSOX6 +KDidt8tH3auX8bFnPWYK0ohkzM9ITE6ycL9kNH+2srKcWGgNLyFkaR7v9P/FIxXAuAFLFdkGw/at I/JaKmUqupRqEdtFN8LWQXlT7VH71wWQCOBK+sYM4cUx3IyVKHbOP2FIW1KxpMGHd7HhA5vhZSqI4 6xSuqy7p4+6va83N8X3WMvI4rhn41U2prx6KV+vYu2c68zLOFAO3RgWE6tSt27GGEDdRXSB53rmyh Zp9X7L4A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x3rFa-00000008Pkm-23OI; Tue, 08 Sep 2026 08:32:18 +0000 Received: from mx1.white.stw.pengutronix.de ([185.203.200.13]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x3rFX-00000008Pih-0PpZ for barebox@lists.infradead.org; Tue, 08 Sep 2026 08:32:16 +0000 Received: from [127.0.1.1] (unknown [IPv6:2a02:560:5dd5:4b00:9ebf:dff:fe00:fdb5]) (Authenticated sender: sha@pengutronix.de) by mx1.white.stw.pengutronix.de (Postfix) with ESMTPSA id 787B3202062; Tue, 08 Sep 2026 10:32:11 +0200 (CEST) From: Sascha Hauer Date: Tue, 08 Sep 2026 10:32:10 +0200 Subject: [PATCH 2/2] fs: reject inodes whose size the superblock cannot address MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260908-fs-filesize-fixes-v1-2-8cf3e781a4d0@pengutronix.de> References: <20260908-fs-filesize-fixes-v1-0-8cf3e781a4d0@pengutronix.de> In-Reply-To: <20260908-fs-filesize-fixes-v1-0-8cf3e781a4d0@pengutronix.de> To: BAREBOX X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1788856331; l=2505; i=s.hauer@pengutronix.de; s=20230412; h=from:subject:message-id; bh=mVEVk4LZ5IBe6pocDUNdk8qwE2uxWCkdc1TXUw9x068=; b=UWaXpRZbDbIfM5OuqqtepWBWN0Z9bnq0Tlfrj7dOZsAzH8NkZ1QWrn2pOt+3MK896kUxbzNI3 JtkA3YPYthCDkhi+AmCbrb/8XMP8VFvzw1KCHwRWFCEdjdkyt8Lkjul X-Developer-Key: i=s.hauer@pengutronix.de; a=ed25519; pk=4kuc9ocmECiBJKWxYgqyhtZOHj5AWi7+d0n/UjhkwTg= X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260908_013215_290987_2B45F73F X-CRM114-Status: GOOD ( 12.56 ) X-Spam-Score: -1.9 (-) X-Spam-Report: Spam detection software, running on the system "bombadil.infradead.org", has NOT identified this incoming email as spam. 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Content preview: f_size is an alias for the inode's i_size, and filesystems read that size straight from untrusted media. ext4's ext4_isize() builds it as ((loff_t)size_high << 32) | size, so bit 31 of size_high lands [...] Content analysis details: (-1.9 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record -0.0 SPF_HELO_PASS SPF: HELO matches SPF record -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] 0.0 DMARC_MISSING Missing DMARC policy 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-Rspamd-Server: mx1 X-Stat-Signature: yne4h7kw1xat7u4m6kqi4nrdxfkmxup4 X-Rspamd-Queue-Id: 7BCC8201CD1 X-Spamd-Result: default: False [-57.41 / 15.00]; RECEIVED_AUTHENTICATED_BY_MX1(-50.00)[]; BAYES_HAM(-3.00)[99.99%]; DWL_DNSWL_MED(-2.00)[infradead.org:dkim]; KNOWN_LIST_ID(-1.00)[barebox.lists.infradead.org]; RCVD_DKIM_ARC_DNSWL_MED(-0.50)[]; R_SPF_ALLOW(-0.20)[+mx:c]; RCVD_IN_DNSWL_MED(-0.20)[2607:7c80:54:3::133:from]; MAILLIST(-0.20)[mailman]; R_DKIM_ALLOW(-0.20)[lists.infradead.org:s=bombadil.20210309]; MIME_GOOD(-0.10)[text/plain]; HAS_LIST_UNSUB(-0.01)[]; RCVD_COUNT_THREE(0.00)[3]; RECEIVED_HELO_LOCALHOST(0.00)[]; DMARC_NA(0.00)[pengutronix.de]; ARC_NA(0.00)[]; RCVD_TLS_LAST(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[lists.infradead.org:+]; RCPT_COUNT_ONE(0.00)[1]; NEURAL_HAM(-0.00)[-1.000]; FROM_NEQ_ENVFROM(0.00)[s.hauer@pengutronix.de,barebox-bounces@lists.infradead.org]; FROM_HAS_DN(0.00)[]; TAGGED_FROM(0.00)[lore=pengutronix.de]; MID_RHS_MATCH_FROM(0.00)[]; ASN(0.00)[asn:7247, ipnet:2607:7c80:54::/48, country:US]; RCVD_VIA_SMTP_AUTH(0.00)[]; FORGED_RECIPIENTS_MAILLIST(0.00)[]; FORGED_SENDER_MAILLIST(0.00)[] X-Rspamd-Action: no action f_size is an alias for the inode's i_size, and filesystems read that size straight from untrusted media. ext4's ext4_isize() builds it as ((loff_t)size_high << 32) | size, so bit 31 of size_high lands in the sign bit; squashfs takes an unchecked le64 for LREG inodes. A negative i_size then feeds the offset arithmetic in __read(), __write() and friends, where it either wraps a size_t count to something huge or -- depending on whether size_t is 32 or 64 bit -- turns the comparison unsigned and skips the EOF clamp altogether. Catch this the way Linux does: give the superblock a ceiling and refuse sizes beyond it, instead of hardening every arithmetic site. Default s_maxbytes to MAX_LFS_FILESIZE in init_super(), which runs before the driver probe, so the filesystems that already lower it (jffs2, ubifs, squashfs, 9p) keep doing so and everyone else stops sitting at zero. The check goes into do_dentry_open() rather than into iget: ten drivers only learn the size in their ->open() callback and write it to the inode through file->f_size, so a lookup time check would miss them. Casting to u64 makes a negative size exceed any sane s_maxbytes, so the sign is covered too; streaming files carry no size of their own and are exempted on the i_stream flag rather than on an i_size value. Assisted-by: Claude:claude-opus-5 Signed-off-by: Sascha Hauer --- fs/fs.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/fs/fs.c b/fs/fs.c index 85881f6cf1..29478cb419 100644 --- a/fs/fs.c +++ b/fs/fs.c @@ -998,6 +998,7 @@ int fsdev_open_cdev(struct fs_device *fsdev) static void init_super(struct super_block *sb) { INIT_LIST_HEAD(&sb->s_inodes); + sb->s_maxbytes = MAX_LFS_FILESIZE; } static int fsdev_umount(struct fs_device *fsdev) @@ -2627,6 +2628,14 @@ static int rmdirat(int dirfd, const char *pathname) return errno_set(error); } +static bool i_size_valid(struct inode *inode) +{ + if (inode->i_stream) + return true; + + return (u64)inode->i_size <= inode->i_sb->s_maxbytes; +} + static int do_dentry_open(struct file *f) { int error; @@ -2642,6 +2651,12 @@ static int do_dentry_open(struct file *f) return error; } + if (!i_size_valid(f->f_inode)) { + dev_warn(&f->fsdev->dev, "%s: bad i_size value: %lld\n", + f->path, f->f_size); + return -EUCLEAN; + } + if (f->f_flags & O_TRUNC) { error = fsdev_truncate(f, 0); f->f_size = 0; -- 2.47.3