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=1794361154; b=ZkcQjo9e6K3w0u5o9QoZEOzSW6Bfk0KmLGfaudPtkHt+x1D9R4zsSlplSOUhTwsTKxnm +sMDOztegzPT+SK43i6XGivMn5TqsDwwzrVbryCNb6F37ZTlytJXgTU91MUrrZUT7lihW ixupPNTrFDpaTbBGXqtmOan7mNUlYxHr2sEI1tqA7qLa6SDZhDuQwEToY79PXz7KbYbi9 GZ5KXW9oPsAYntEh3OZcWq13w+AANjX47gcDZag/xCA8GtXiwx/okXfmzANNkYr4xIHWc cXB+Cg1+Jxr4E9iBk+d/ic8T5KSgmXHgx2dLcFh56SvugPmj4nxx2GB8/Q+CH+tPbhA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794361154; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=q1XMXCfORYIrKm93fQ6DxDjTZ8J9zWMbzTkss/pm2Tw=; b=ISNvQ5UtJGWX6YDSJxq0ZHfzlmgWU76dVj+cvqPm1FbAO9bxYtMOrkw+qwQ5EMxszygm BiGKqzoa5fQ1EbYeX9IP5sdhhXVrz4Pp0zCR+RECTWxokxczdfhzRfiwilCJbdLxOO+jm qfYz2j9l5o8N06hjRhfltNqMvHItjkGVn0zYsZJ5yhS2Zhvtw7LlxnqSL88tIItKkUpsJ NG6U/4bl6xVJs6bLuA1jZ4URWIbLm0eo31ES6sxzErjEGi/r3W3xxuZhi7mNBULNL01LN 9K/KzJmBthvbTzqJv1H/tB94ANX7F2tKhMVVZ0IfnHrzsME8Y5FiiHNiiaiudNu7BYQ== 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=J5CaK7DH; 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 730E0606A324 for ; Wed, 11 Nov 2026 01:39:14 +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=J5CaK7DH Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5B411F0089F; Wed, 11 Nov 2026 01:39:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794361154; bh=q1XMXCfORYIrKm93fQ6DxDjTZ8J9zWMbzTkss/pm2Tw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=J5CaK7DHLhd1E/o34r5P8EzSZWAh2TckCz2auU/0GLeJ5x+saJdIsB5AqBubY1Sll KKJwLHcNMpGPy8uM+B4W2tltgP/TSZlek+aPQKmvNSrMLumBp7/EMxuVOO7Ek98ghz pLzfzWFFmkOAb/ag/jcLYQhpuovfxYAPly2qrt3FFTqvsF3BecmBwnY/YCnGm5WB5f MKxt6wDDrm/uL6EI0aBtO7AWrRvPrEkhxATOTO271MN+cEGe8hjaZ9dFnv56l0Wcif neLdzyE4qoYKdIqFIPGLALwwazO/VdkdiAvKifSnk1pCNKIO0vGHPxmztRt+uZsuzA wc5Kysm1njxvA== From: Sasha Levin To: stable@vger.kernel.org Cc: Yuejie Shi , Konstantin Komarov , Sasha Levin Subject: [PATCH 6.6.y 3/3] fs/ntfs3: validate the EA value length in ntfs_read_ea() Date: Tue, 10 Nov 2026 20:39:10 -0500 Message-ID: <20261111013841.400667-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261111013841.400667-1-sashal@kernel.org> References: <20261107054019-failed-6.6-351817226fbf@kernel.org> <20261111013841.400667-1-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 5af61c90cc234..1c18ab072987b 100644 --- a/fs/ntfs3/xattr.c +++ b/fs/ntfs3/xattr.c @@ -146,49 +146,32 @@ 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