From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794362249; b=SAnOx1HTnRzN9BPT+bxa1kawAiq7amOavkSzrBMQx+L0z17KkOqmFBW2yE2iT9LZPqNY 2xjRI8VckYCVraTIm7RExkghO8JonCTd5mhHZ2cIHD99kpEjK8Aq+dhY5KHEZrKA3KRCh BCezFCX9cXTsSwIZI9RTbvX83XUquZ7raVRwdkINh+pFhmg1oMWO3o8wMY+9pykzfGpbT y4+/3hxqZ9Y/XpbJ9lRaLWxaFIihB6lwWDIVAarnclYAiqN6H2UIYqBMoHm8/gqnr4psN BV6gQOFLX/aWrgnOIjQl9qt0NNDAYjfLvU1+87yjXyI2Hy7JE4zWj9cD2oYNAQzoNVw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794362249; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=Q8ntp7OOo/jbTOHv3d2t7vhlxuUXfMnlFOOMXnHKIo4=; b=imWR/htRPNjD0SeHGFgSc0jEqUY99FfVSX10Ywcx/x/L8skrbDaFGYAdsUvt2/dP9Z7Q OrLe2RWWSDVLk12yR/5g8YgSbbuOx1NocExcO37QfhzRFMdtMT20nNZTjoglqDB2+Y2wm RFL41q3XDeThNgAwhrik1zsjnwNkAJfEUiYPprQHlvjg3z5eT1QnDZmOaPvFRpMTZfSNs FtWgojR90kMpDFooSCAflkXnAfxtB9byb2dpmfN+gu0b/1BlL81Em5mjMofIZ52H56RFt +3kfsVRDOVd3eZL+AwpHrcDPBfNlXWnb6MWvr0BIdrICQufjGFngQ+jiGlpZmCjKCfQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="FFaFsb/8"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 73281606A324 for ; Wed, 11 Nov 2026 01:57:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=FFaFsb/8 Received: by smtp.kernel.org (Postfix) with ESMTPSA id BACE61F0093C; Wed, 11 Nov 2026 01:57:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794362249; bh=Q8ntp7OOo/jbTOHv3d2t7vhlxuUXfMnlFOOMXnHKIo4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=FFaFsb/8cTDUxOSjnotrClUivXlaI3eGrUwbXTv6zP5VG2yjz5W/cvB6Qj3qTiuX+ 20LOpBiQz9yX7SR+AWUZw2FJeiL9aIL1LZ67NTt0qpmtgKnzSoM1DhTih9Fy+SKRQM aniJ+9O4rbWR0v1xEUBAT7rV79qrmEm7cD1cM5uioJoTLYEqJ0DgsYykMRwld9EyLo X28Dyi4FZH3ZiailLZhMrBWEq0BkH+8tj2RJ7qobn8tiOEi4lP6lzbwyTQMyx8RVHD 1LQ/quZg4yPW/PkeAlbXSvCCQWYPhzam/Qp2TexvZseJ/bd8geKQd/u6CaOapa6RO5 PSxFlbhc8LV+g== From: Sasha Levin To: stable@vger.kernel.org Cc: Yuejie Shi , Konstantin Komarov , Sasha Levin Subject: [PATCH 5.15.y 3/3] fs/ntfs3: validate the EA value length in ntfs_read_ea() Date: Tue, 10 Nov 2026 20:57:25 -0500 Message-ID: <20261111015355.444686-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261111015355.444686-1-sashal@kernel.org> References: <20261107061313-failed-5.15-351817226fbf@kernel.org> <20261111015355.444686-1-sashal@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Yuejie Shi [ Upstream commit 351817226fbf0031c4c63d1f5d7f15c3172312eb ] ntfs_read_ea() checks the $EA list for consistency, but it only recomputes the packed size of an entry when the entry's own size field is zero: for (off = 0; off < size; off += ea_size) { const struct EA_FULL *ef = Add2Ptr(ea_p, off); u32 bytes = size - off; ... if (ef->size) { ea_size = le32_to_cpu(ef->size); if (ea_size > bytes) goto out1; continue; /* <- elength never checked */ } ... ea_size = ALIGN(struct_size(ef, name, 1 + ef->name_len + le16_to_cpu(ef->elength)), 4); if (ea_size > bytes) goto out1; } ef->size is non-zero for every entry except the last one, and it is what ntfs3 itself writes (ntfs_set_ea() stores exactly that aligned packed size), so in practice elength is not validated at all. find_ea() then uses unpacked_ea_size(), which also prefers ea->size when it is set, so it agrees and hands the entry back. ntfs_get_ea() copies elength bytes with no further bound of its own: len = le16_to_cpu(ea->elength); ... if (len > size) { /* size is the *caller's* buffer */ err = -ERANGE; ... } memcpy(buffer, ea->name + ea->name_len + 1, len); so a caller that supplies a large enough buffer receives up to 64 KiB of whatever follows the small $EA allocation -- straight to userspace via getxattr(2). Compute the packed size unconditionally and require it to fit in the entry. Hoist the "bytes < offsetof(struct EA_FULL, name)" test above the ef->size branch as well: name_len and elength were being read there without it, which is itself a small over-read of the kmalloc'd buffer when fewer than 8 bytes are left. The old "bytes < sizeof(ef->size)" test is subsumed by it. # mkntfs image; create /mnt/ntfs/poc with user.ntfs6 set, then rewrite # that EA_FULL's elength from 0xf to 0xff00 on the raw device mount -t ntfs3 -o ro /dev/vda /mnt/ntfs getxattr("/mnt/ntfs/poc", "user.ntfs6", buf, 128 * 1024); BUG: KASAN: slab-out-of-bounds in ntfs_get_ea+0x294/0x3e0 Read of size 65280 at addr ffff0000cca53acf by task xattr_probe/142 __asan_memcpy+0x3c/0xa0 ntfs_get_ea+0x294/0x3e0 ntfs_getxattr+0x284/0x318 __vfs_getxattr+0x104/0x160 vfs_getxattr+0x1b4/0x1e0 do_getxattr+0xcc/0x230 path_getxattrat+0x184/0x270 __arm64_sys_getxattr+0x64/0x80 Allocated by task 142: __kmalloc_noprof+0x294/0x668 ntfs_read_ea+0x1e4/0x420 ntfs_get_ea+0x2c8/0x3e0 The buggy address belongs to the object at ffff0000cca53a80 which belongs to the cache kmalloc-96 of size 96 The object being over-read is the one ntfs_read_ea() just allocated, and it is 96 bytes. Entries written by ntfs3 and by Windows set size to the aligned packed size, so the new test does not reject anything a working filesystem produces. Fixes: be71b5cba2e6 ("fs/ntfs3: Add attrib operations") Cc: stable@vger.kernel.org Signed-off-by: Yuejie Shi [almaz.alexandrovich@paragon-software.com: applied as-is, logic is the same but the code is cleaner] Signed-off-by: Konstantin Komarov Signed-off-by: Sasha Levin --- fs/ntfs3/xattr.c | 45 ++++++++++++++------------------------------- 1 file changed, 14 insertions(+), 31 deletions(-) diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c index ee2f38b912d23..078f4abb42ec2 100644 --- a/fs/ntfs3/xattr.c +++ b/fs/ntfs3/xattr.c @@ -145,49 +145,32 @@ static int ntfs_read_ea(struct ntfs_inode *ni, struct EA_FULL **ea, for (off = 0; off < size; off += ea_size) { const struct EA_FULL *ef = Add2Ptr(ea_p, off); u32 bytes = size - off; - size_t need; - - /* Check if we can use field ea->size. */ - if (bytes < sizeof(ef->size)) - goto out1; + u32 packed_size; /* Check if we can use fields ef->name_len and ef->elength. */ if (bytes < offsetof(struct EA_FULL, name)) goto out1; - /* Size needed to hold this record's name and value. */ - need = struct_size(ef, name, - 1 + ef->name_len + le16_to_cpu(ef->elength)); + /* + * The name and the value have to fit in the entry whether or + * not ef->size is set, because ntfs_get_ea() copies elength + * bytes out of this buffer and checks them only against the + * caller supplied buffer size. + */ + packed_size = + ALIGN(struct_size(ef, name, + 1 + ef->name_len + + le16_to_cpu(ef->elength)), + 4); if (ef->size) { ea_size = le32_to_cpu(ef->size); - /* ef->size must fit the list and cover the record. */ - if (ea_size > bytes || ea_size < need) - goto out1; - if (bytes < offsetof(struct EA_FULL, name)) - goto out1; - - /* Check if we can use fields ef->name_len and ef->elength. */ - if (bytes < offsetof(struct EA_FULL, name)) - goto out1; - - /* - * The declared entry size (ef->size) must be large - * enough to hold the name and value. Otherwise a later - * reader such as ntfs_get_ea() copies ef->elength bytes - * starting past the entry, reading out of bounds of the - * ea buffer and leaking adjacent heap memory to - * userspace via getxattr(). - */ - if (struct_size(ef, name, - 1 + ef->name_len + - le16_to_cpu(ef->elength)) > - ea_size) + if (ea_size > bytes || packed_size > ea_size) goto out1; continue; } - ea_size = ALIGN(need, 4); + ea_size = packed_size; if (ea_size > bytes) goto out1; } -- 2.53.0