From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yx2-f13.google.com (mail-yx2-f13.google.com [74.125.224.141]) (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 DC16E5437C7 for ; Wed, 16 Sep 2026 18:33:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.224.141 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789583641; cv=none; b=j7RmeQ/TZdfsNfoug6b8FZHUBUA1G3bhWUwiSDKm3N8ytbQazEz8IHIkgsJ76nVCqKOdTpP4oAVBpaOsfPVu1aBjnEaT1sxv4U20zSkGevUXYwUwvSP1ShlX9TCut1k5rtQHzYgz1QA3JrW6U0qaWYZqBnNObhIuT2u67hpjTbk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789583641; c=relaxed/simple; bh=kCZFspvHZ9tRLjdxKXZWCpHLq8aaBrTCKUoD7EZAf1g=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=uXhzdvRNZnuUju1Ri0MS35LH4dOYHTBSIe25DVS7FjVsWPfZ9jwn7pwVAFphPpmgVAW17xfhrR2/nf3zu1VcnhlfvDvY8j64CqtlZ4fbIxqtG7+et0cNko/vHhC6j4lFmAJen3NcVc1tx3F9+7iQE8/fv3/7nRUbwgBZTYCxH0Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=dubeyko.com; spf=pass smtp.mailfrom=dubeyko.com; dkim=pass (2048-bit key) header.d=dubeyko-com.20251104.gappssmtp.com header.i=@dubeyko-com.20251104.gappssmtp.com header.b=t+kBPlb+; arc=none smtp.client-ip=74.125.224.141 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=dubeyko.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=dubeyko.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=dubeyko-com.20251104.gappssmtp.com header.i=@dubeyko-com.20251104.gappssmtp.com header.b="t+kBPlb+" Received: by mail-yx2-f13.google.com with SMTP id 00721157ae682-85d4ddd17a0so10911737b3.0 for ; Wed, 16 Sep 2026 11:33:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dubeyko-com.20251104.gappssmtp.com; s=20251104; t=1789583622; x=1790188422; darn=vger.kernel.org; h=mime-version:user-agent:content-transfer-encoding:content-type :autocrypt:references:in-reply-to:date:cc:to:from:subject:message-id :from:to:cc:subject:date:message-id:reply-to:content-type; bh=kCZFspvHZ9tRLjdxKXZWCpHLq8aaBrTCKUoD7EZAf1g=; b=t+kBPlb+sYWlxw6U7veBMpcQR4IDn3qj36nXmr8vnA9Lu21/LKbuUGgRrx42xwXa3I wqeXKSqlEfVNL90+F5oUFExWmM9riBtmBaM05AW9N01UyZ4V4jLkjP1w8ZfBY4XO7Avs EAHI5EULZ1RIA+t/lJ1+gW69EG1t81nFxOMx/RmudFX92T+mk5DVaQuEg160e1eBg9Mn ryR9Xk1iD1ArhhEE5trEwmXtrrRCxsGDgEk6Qy5TBP79AuiwL3S/jsEoZI/Ddvh0+eDd DrJp7dz0rP35cnHJRfz923LtYERY80AyI9Rjl8CQ75eZbKAssZfHzVN+wx4ILd7JjEJX ZmpA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789583622; x=1790188422; h=mime-version:user-agent:content-transfer-encoding:content-type :autocrypt:references:in-reply-to:date:cc:to:from:subject:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to:content-type; bh=kCZFspvHZ9tRLjdxKXZWCpHLq8aaBrTCKUoD7EZAf1g=; b=LCQh1wQiTiMXD028nwMn3I22MJ/EUyfhnaZIeDarMzt5sDNlvCGeOiLcbKQNuL3yyR 8/RhhXWSmrwwVFL/Cb6wTOomurgre0nnXe45FMSKhGT1DDZzx+pc+Wk5E85JVAGR8M7K Wt8c69NPewOTjJXMvubji3ZYrTO1Gzbw7yIUZ+CxM8veKU+k8RtENiULWOkzclP88W9q FH/nyTyvF56ECAqlqHB6c7HpssuWTuxV90oyV5raVkxTy/THcQX26JRIbxPMFSItN6OT qPxWzmzSHVDaY7o45cPTcYbRrX2gAu1BRwoxZIg3CcLNTfVYZxn4L0MZ7bq0LzZP9tJa Q5Cg== X-Gm-Message-State: AFuF++nU4rXzzBJF3YU7xNxCvcXqgI3iuxtCUEl9BBQ+Mn9NlUXfOTOI NeotvhZQOvezJF4bVWcxsSXZTlTgtzFnkeuF6oFWJgn439FL/EfZKnB4RGfhva3wuS2MTgYKNXX Q/aud5dBhTA== X-Gm-Gg: AYBFou3KvhSkwVySlA8RutgrfYPr5ztPX74J3H0X33EwgvAeYNPuldtH/qUKQ3Z8Jmz ni73uEbJv/zQ/v6dfD0NaQOoD24OozXniZVlbgJVEL51SGQUXgtpmEbdHdHNPYo7Ct9vmtxyvjB zrjD731jbgmKoMNblD/ZK2yw5WfgYhdjrAi7Cuyb7ObOltw2f/Vdoi3PKzO5Jli6kx3Xi2TC2AN ONzPx3M8mElbifTVBmuHc8ffmKdlPimCr5k4bNXbkf0MS1I7LInmxTM5dG/VbYUURK2N1HBlVo2 eJ7Znk1xs0g2xreJtOy6WOPhDEdVHko1ekOByVReX01wcrfU/nFwkx5qotNKh+yVKjLoy2mBSgi TzLXuDLhudtshMKPz/SMY+g3W8d++8MVBusibBnuAJ8nUgBEKk1u/jfhUQbTKxuyxV1Key2iTuv 6i5sBnVw0RZuGv3wpFRjBVGWVBkjQCK2TmHmUXV6PS0a5aArXlIZ2rDPniaewNC6LUKRYJGZQ+G j6UCL8YNfV60WqqZb1ahoxLuiTuQuMths2fXXqvKeLNMCjhJIr3oGrNk3rLb2SBoLFkGDb3HdHs QnBFJeZfdaD8RB+snb3x6E3yMIgoEBOOcY0vGgZtJIfBBtKFDPPRk17NJJ+Sjmmj X-Received: by 2002:a05:690e:1918:b0:671:3e63:2e91 with SMTP id 956f58d0204a3-671632d88a4mr1650293d50.36.1789583622221; Wed, 16 Sep 2026 11:33:42 -0700 (PDT) Received: from ?IPv6:2600:1700:6476:1430:f547:a2c0:72f7:6671? ([2600:1700:6476:1430:f547:a2c0:72f7:6671]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-6715f6df1a6sm1653225d50.8.2026.09.16.11.33.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Sep 2026 11:33:41 -0700 (PDT) Message-ID: Subject: Re: [PATCH 1/1] hfs: don't let internal B-tree inodes leak into the VFS open path From: Viacheslav Dubeyko To: 1sh1ro , John Paul Adrian Glaubitz , Yangtao Li Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Mateusz Guzik , Christian Brauner , stable@vger.kernel.org Date: Wed, 16 Sep 2026 11:33:38 -0700 In-Reply-To: References: <20260916080000.0-hfs-fix@localhost> Autocrypt: addr=slava@dubeyko.com; prefer-encrypt=mutual; keydata=mQINBGgaTLYBEADaJc/WqWTeunGetXyyGJ5Za7b23M/ozuDCWCp+yWUa2GqQKH40dxRIR zshgOmAue7t9RQJU9lxZ4ZHWbi1Hzz85+0omefEdAKFmxTO6+CYV0g/sapU0wPJws3sC2Pbda9/eJ ZcvScAX2n/PlhpTnzJKf3JkHh3nM1ACO3jzSe2/muSQJvqMLG2D71ccekr1RyUh8V+OZdrPtfkDam V6GOT6IvyE+d+55fzmo20nJKecvbyvdikWwZvjjCENsG9qOf3TcCJ9DDYwjyYe1To8b+mQM9nHcxp jUsUuH074BhISFwt99/htZdSgp4csiGeXr8f9BEotRB6+kjMBHaiJ6B7BIlDmlffyR4f3oR/5hxgy dvIxMocqyc03xVyM6tA4ZrshKkwDgZIFEKkx37ec22ZJczNwGywKQW2TGXUTZVbdooiG4tXbRBLxe ga/NTZ52ZdEkSxAUGw/l0y0InTtdDIWvfUT+WXtQcEPRBE6HHhoeFehLzWL/o7w5Hog+0hXhNjqte fzKpI2fWmYzoIb6ueNmE/8sP9fWXo6Av9m8B5hRvF/hVWfEysr/2LSqN+xjt9NEbg8WNRMLy/Y0MS p5fgf9pmGF78waFiBvgZIQNuQnHrM+0BmYOhR0JKoHjt7r5wLyNiKFc8b7xXndyCDYfniO3ljbr0j tXWRGxx4to6FwARAQABtCZWaWFjaGVzbGF2IER1YmV5a28gPHNsYXZhQGR1YmV5a28uY29tPokCVw QTAQoAQQIbAQUJA8JnAAULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBFXDC2tnzsoLQtrbBDlc2cL fhEB1BQJoGl5PAhkBAAoJEDlc2cLfhEB17DsP/jy/Dx19MtxWOniPqpQf2s65enkDZuMIQ94jSg7B F2qTKIbNR9SmsczjyjC+/J7m7WZRmcqnwFYMOyNfh12aF2WhjT7p5xEAbvfGVYwUpUrg/lcacdT0D Yk61GGc5ZB89OAWHLr0FJjI54bd7kn7E/JRQF4dqNsxU8qcPXQ0wLHxTHUPZu/w5Zu/cO+lQ3H0Pj pSEGaTAh+tBYGSvQ4YPYBcV8+qjTxzeNwkw4ARza8EjTwWKP2jWAfA/ay4VobRfqNQ2zLoo84qDtN Uxe0zPE2wobIXELWkbuW/6hoQFPpMlJWz+mbvVms57NAA1HO8F5c1SLFaJ6dN0AQbxrHi45/cQXla 9hSEOJjxcEnJG/ZmcomYHFneM9K1p1K6HcGajiY2BFWkVet9vuHygkLWXVYZ0lr1paLFR52S7T+cf 6dkxOqu1ZiRegvFoyzBUzlLh/elgp3tWUfG2VmJD3lGpB3m5ZhwQ3rFpK8A7cKzgKjwPp61Me0o9z HX53THoG+QG+o0nnIKK7M8+coToTSyznYoq9C3eKeM/J97x9+h9tbizaeUQvWzQOgG8myUJ5u5Dr4 6tv9KXrOJy0iy/dcyreMYV5lwODaFfOeA4Lbnn5vRn9OjuMg1PFhCi3yMI4lA4umXFw0V2/OI5rgW BQELhfvW6mxkihkl6KLZX8m1zcHitCpWaWFjaGVzbGF2IER1YmV5a28gPFNsYXZhLkR1YmV5a29Aa WJtLmNvbT6JAlQEEwEKAD4WIQRVwwtrZ87KC0La2wQ5XNnC34RAdQUCaBpd7AIbAQUJA8JnAAULCQ gHAgYVCgkICwIEFgIDAQIeAQIXgAAKCRA5XNnC34RAdYjFEACiWBEybMt1xjRbEgaZ3UP5i2bSway DwYDvgWW5EbRP7JcqOcZ2vkJwrK3gsqC3FKpjOPh7ecE0I4vrabH1Qobe2N8B2Y396z24mGnkTBbb 16Uz3PC93nFN1BA0wuOjlr1/oOTy5gBY563vybhnXPfSEUcXRd28jI7z8tRyzXh2tL8ZLdv1u4vQ8 E0O7lVJ55p9yGxbwgb5vXU4T2irqRKLxRvU80rZIXoEM7zLf5r7RaRxgwjTKdu6rYMUOfoyEQQZTD 4Xg9YE/X8pZzcbYFs4IlscyK6cXU0pjwr2ssjearOLLDJ7ygvfOiOuCZL+6zHRunLwq2JH/RmwuLV mWWSbgosZD6c5+wu6DxV15y7zZaR3NFPOR5ErpCFUorKzBO1nA4dwOAbNym9OGkhRgLAyxwpea0V0 ZlStfp0kfVaSZYo7PXd8Bbtyjali0niBjPpEVZdgtVUpBlPr97jBYZ+L5GF3hd6WJFbEYgj+5Af7C UjbX9DHweGQ/tdXWRnJHRzorxzjOS3003ddRnPtQDDN3Z/XzdAZwQAs0RqqXrTeeJrLppFUbAP+HZ TyOLVJcAAlVQROoq8PbM3ZKIaOygjj6Yw0emJi1D9OsN2UKjoe4W185vamFWX4Ba41jmCPrYJWAWH fAMjjkInIPg7RLGs8FiwxfcpkILP0YbVWHiNAabQoVmlhY2hlc2xhdiBEdWJleWtvIDx2ZHViZXlr b0BrZXJuZWwub3JnPokCVAQTAQoAPhYhBFXDC2tnzsoLQtrbBDlc2cLfhEB1BQJoVemuAhsBBQkDw mcABQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAAAoJEDlc2cLfhEB1GRwP/1scX5HO9Sk7dRicLD/fxo ipwEs+UbeA0/TM8OQfdRI4C/tFBYbQCR7lD05dfq8VsYLEyrgeLqP/iRhabLky8LTaEdwoAqPDc/O 9HRffx/faJZqkKc1dZryjqS6b8NExhKOVWmDqN357+Cl/H4hT9wnvjCj1YEqXIxSd/2Pc8+yw/KRC AP7jtRzXHcc/49Lpz/NU5irScusxy2GLKa5o/13jFK3F1fWX1wsOJF8NlTx3rLtBy4GWHITwkBmu8 zI4qcJGp7eudI0l4xmIKKQWanEhVdzBm5UnfyLIa7gQ2T48UbxJlWnMhLxMPrxgtC4Kos1G3zovEy Ep+fJN7D1pwN9aR36jVKvRsX7V4leIDWGzCdfw1FGWkMUfrRwgIl6i3wgqcCP6r9YSWVQYXdmwdMu 1RFLC44iF9340S0hw9+30yGP8TWwd1mm8V/+zsdDAFAoAwisi5QLLkQnEsJSgLzJ9daAsE8KjMthv hUWHdpiUSjyCpigT+KPl9YunZhyrC1jZXERCDPCQVYgaPt+Xbhdjcem/ykv8UVIDAGVXjuk4OW8la nf8SP+uxkTTDKcPHOa5rYRaeNj7T/NClRSd4z6aV3F6pKEJnEGvv/DFMXtSHlbylhyiGKN2Amd0b4 9jg+DW85oNN7q2UYzYuPwkHsFFq5iyF1QggiwYYTpoVXsw Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.1 (by Flathub.org) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2026-09-16 at 17:09 +0800, 1sh1ro wrote: > hfs_btree_open() creates the extents and catalog B-tree inodes with > iget_locked() and never assigns them a file type, so both stay cached > with i_mode =3D=3D 0 after mount. >=20 > A crafted HFS image whose catalog contains a record whose DirID/FlNum > aliases HFS_EXT_CNID (3) or HFS_CAT_CNID (4) makes hfs_lookup() -> > hfs_iget() -> iget5_locked() return that already-cached internal > inode > (hfs_test_inode() only compares i_ino), without running > hfs_read_inode().=C2=A0 The typeless inode then reaches the generic open > path and, with CONFIG_DEBUG_VFS=3Dy, deterministically panics: >=20 > =C2=A0 VFS_BUG_ON_INODE(!IS_ANON_FILE(inode)): inode:... fs:hfs mode:0 > opflags:0xc flags:0x0 state:0x0 count:2 > =C2=A0 ------------[ cut here ]------------ > =C2=A0 kernel BUG at fs/namei.c:4271! > =C2=A0 RIP: 0010:may_open+0x2ba/0x480 fs/namei.c:4271 > =C2=A0 Call Trace: > =C2=A0=C2=A0 do_open fs/namei.c:4698 [inline] > =C2=A0=C2=A0 path_openat+0x1600/0x3de0 fs/namei.c:4863 > =C2=A0=C2=A0 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1385 >=20 > Fix it in two steps: >=20 > =C2=A0- give the B-tree inodes an S_IFREG type in hfs_btree_open(), so th= e > =C2=A0=C2=A0 "every cached inode has a valid S_IFMT type" VFS invariant h= olds > =C2=A0=C2=A0 regardless of what is on disk; >=20 > =C2=A0- refuse, in hfs_iget(), catalog records that address the reserved > =C2=A0=C2=A0 B-tree CNIDs so a malformed image cannot alias internal obje= cts > =C2=A0=C2=A0 into dentries at all.=C2=A0 Returning NULL follows the exist= ing > =C2=A0=C2=A0 convention for unaddressable records: hfs_fill_super() turns= it > =C2=A0=C2=A0 into a mount failure and hfs_lookup() into -EACCES. >=20 > Without CONFIG_DEBUG_VFS the assertion compiles away and the same > crafted image silently makes a typeless inode openable, so this is > not > merely a debug-config nuisance. >=20 > Found by syzkaller-style fuzzing of v7.2-rc7; still reproducible on > current mainline. >=20 > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Signed-off-by: 1sh1ro > --- > =C2=A0fs/hfs/btree.c | 8 ++++++++ > =C2=A0fs/hfs/inode.c | 11 +++++++++++ > =C2=A02 files changed, 19 insertions(+) >=20 > diff --git a/fs/hfs/btree.c b/fs/hfs/btree.c > index 2eb37a2f64e8..bd69ace8f309 100644 > --- a/fs/hfs/btree.c > +++ b/fs/hfs/btree.c > @@ -43,6 +43,14 @@ struct hfs_btree *hfs_btree_open(struct > super_block *sb, u32 id, btree_keycmp ke > =C2=A0=C2=A0=C2=A0 if (!tree->inode) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 goto free_tree; > =C2=A0=C2=A0=C2=A0 BUG_ON(!(inode_state_read_once(tree->inode) & I_NEW)); > + > +=C2=A0=C2=A0 /* B-tree inodes are internal objects that must never be ex= posed > +=C2=A0=C2=A0=C2=A0 * through directory entries.=C2=A0 Give them a REG ty= pe so the VFS > +=C2=A0=C2=A0=C2=A0 * invariant "every cached inode has a valid S_IFMT ty= pe" holds > even > +=C2=A0=C2=A0=C2=A0 * when a corrupted image contains catalog records ali= asing these > +=C2=A0=C2=A0=C2=A0 * reserved CNIDs. > +=C2=A0=C2=A0=C2=A0 */ > +=C2=A0=C2=A0 tree->inode->i_mode =3D S_IFREG; In HFS+ we call hfsplus_iget() in hfs_btree_open() [1] and it assign the S_IFREG in hfsplus_system_read_inode() [2]. But in HFS we call iget_locked() instead. I think we need to call hfs_iget() there and to have something like hfs_system_read_inode() that will assign S_IFREG to the i_mode. But current fix doesn't look like right solution now. Could you please explore this direction for the fix? Thanks, Slava. > =C2=A0=C2=A0=C2=A0 { > =C2=A0=C2=A0=C2=A0 struct hfs_mdb *mdb =3D HFS_SB(sb)->mdb; > =C2=A0=C2=A0=C2=A0 HFS_I(tree->inode)->flags =3D 0; > diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c > index ac4a9055c5c0..bb759345f1fc 100644 > --- a/fs/hfs/inode.c > +++ b/fs/hfs/inode.c > @@ -432,6 +432,17 @@ struct inode *hfs_iget(struct super_block *sb, > struct hfs_cat_key *key, hfs_cat_ > =C2=A0=C2=A0=C2=A0 default: > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return NULL; > =C2=A0=C2=A0=C2=A0 } > + > +=C2=A0=C2=A0 /* Refuse catalog records that address the internal B-tree > objects: > +=C2=A0=C2=A0=C2=A0 * a crafted image can otherwise make hfs_lookup() ret= urn the > cached > +=C2=A0=C2=A0=C2=A0 * typeless B-tree inode, which then reaches may_open(= ) with > +=C2=A0=C2=A0=C2=A0 * i_mode =3D=3D 0 and trips VFS_BUG_ON_INODE() there.= =C2=A0 NULL follows > the > +=C2=A0=C2=A0=C2=A0 * existing convention for unaddressable records (moun= t failure / > +=C2=A0=C2=A0=C2=A0 * -EACCES). > +=C2=A0=C2=A0=C2=A0 */ > +=C2=A0=C2=A0 if (cnid =3D=3D HFS_EXT_CNID || cnid =3D=3D HFS_CAT_CNID) > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return NULL; > + > =C2=A0=C2=A0=C2=A0 inode =3D iget5_locked(sb, cnid, hfs_test_inode, hfs_r= ead_inode, > &data); > =C2=A0=C2=A0=C2=A0 if (inode && (inode_state_read_once(inode) & I_NEW)) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unlock_new_inode(inode); > -- > 2.39.5 [1] https://elixir.bootlin.com/linux/v7.3-rc3/source/fs/hfsplus/btree.c#L286 [2] https://elixir.bootlin.com/linux/v7.3-rc3/source/fs/hfsplus/super.c#L60