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=1794360659; b=3l75TdOGHxDRRLA2Q0nME57/GnMHbJGxDba859NonLvPet3N1MkqHE8Dq7Tcibl56/ua NlCp5MtsIm80LME5W0znf6TRGnYFbGUG2BcQ4BHa1Y68DU9TD7uCOd2DYSQRIH6Iqfod3 ZSo7IMA7QshVXmMDT8lMxOKVL9eYFSb/yDM/n2PzPjrC7L+iyrcMBiQVX5Ue80R7lsu/E VcjuViCAej2FBuyS1KFyIiyUytpdhaaZ7VrKYzGJFpOWg7QdpfgO0IMCU0V7fx1X9XB7U Qbjd19i9UKN3zoYUXMv2N1b+ME1XkRxzvGGIDf8qtID+wfP8khKMfOYLj6g83ba0cWQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794360659; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=me7HqOtwt9g9w9ZXmVe1A7Yc677bDrgllgMpRwo8kAA=; b=p7lpG7TtPQU4RuMe9zQWtaTSVmNteE+gfgc1KFBobCtaeoYrikCHIX6HVWmtmbb/Ylsu sN2T0daWXG00R9qdl5ieIsuQCTEVmmcr+Ts64x7visbTcKmSbBgDrxqwcVwDdVm+rj/eW wFwInCKUqtKs6dX1odts84wRblkoOTZBPCFBV/JfZ5HDKQ33Ca4Nw+uD6S/KMMtUju4YZ 1q415uQt6tgnk76MZ8Hp8A4sC4tF4XkQB9NwSTGXRrfXva5IVE0qh+3brnKmalz0RP1ku QEVHhiKboVHYhnqc5BkjNeEn8hLCG4QEDAMk9SSCjTg3rYqPZo+MmllzX+L6F7mEiFw== 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=KEvEeZnD; 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 9834F606A327 for ; Wed, 11 Nov 2026 01:30:59 +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=KEvEeZnD Received: by smtp.kernel.org (Postfix) with ESMTPSA id F38A41F0093C; Wed, 11 Nov 2026 01:30:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794360659; bh=me7HqOtwt9g9w9ZXmVe1A7Yc677bDrgllgMpRwo8kAA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=KEvEeZnD8AgAbQZmK62dIaEWNqTFpyGnFvxYNvO7NfJlBRbOiSh6t6Ac7Blz5gz2V eWnChaM4RHeDEZJPrpLOuXITG/0dmFxzN5iLhnMi0VG6FyTiGu72arJnxDC4aXTnW4 TyRGExE0Yetf5qnYcpWpbSE+ZxLJYN2SvYwKe90BAxnF+M0xeo4O7/C6ubN9DVDNjT hcV+jeP3uB90eoSJR2Iq+CoZbr2aUdoIlGKBfpZufyVkhrtJTMdfXfl3IbxQoGP0T0 VMqfOrrdaeropqKjLQxmw6/XLIAfvo9IsXbQBeO5aXfz/hIizdbDAt31hZ243Fyuti fxLh/UATBN/xg== From: Sasha Levin To: stable@vger.kernel.org Cc: Aldo Ariel Panzardo , Konstantin Komarov , Sasha Levin Subject: [PATCH 6.18.y 2/3] fs/ntfs3: validate that EA entry size covers its name and value Date: Tue, 10 Nov 2026 20:30:55 -0500 Message-ID: <20261111013025.390312-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261111013025.390312-1-sashal@kernel.org> References: <20261107051533-failed-6.18-351817226fbf@kernel.org> <20261111013025.390312-1-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: Aldo Ariel Panzardo [ Upstream commit 60bd50014cc9a97c5e34a8bddd2bad4d2dc5acb7 ] ntfs_read_ea() walks the on-disk $EA attribute and checks each EA_FULL entry for consistency. For an entry with a non-zero ef->size (the offset to the next entry) the loop only verifies that this stride fits in the remaining buffer, and then continues: if (ef->size) { ea_size = le32_to_cpu(ef->size); if (ea_size > bytes) goto out1; continue; } It never verifies that the entry's own name (ef->name_len) and value (ef->elength) actually fit inside ef->size. A later reader trusts ef->elength unconditionally; ntfs_get_ea() does: len = le16_to_cpu(ea->elength); /* up to 0xffff */ ... if (len > size) /* size is the user buffer */ return -ERANGE; memcpy(buffer, ea->name + ea->name_len + 1, len); A crafted image with a small but valid ef->size (e.g. 24) and ef->elength == 0xffff therefore passes validation, and a getxattr() with a large enough user buffer copies up to 64 KiB starting just past the short entry -- an out-of-bounds read of the ea_all allocation that leaks adjacent kernel heap memory to userspace. BUG: KASAN: slab-out-of-bounds in ntfs_get_ea+0x2b8/0x3f0 Read of size 65535 ... ntfs_get_ea -> ntfs_getxattr -> vfs_getxattr -> do_getxattr The zero-ef->size branch already computes the same struct_size() to derive the stride; mirror that in the non-zero branch and reject the entry when its declared size cannot hold the name and value. Fixes: 0e8235d28f3a ("fs/ntfs3: Check fields while reading") Cc: stable@vger.kernel.org Signed-off-by: Aldo Ariel Panzardo Signed-off-by: Konstantin Komarov Stable-dep-of: 351817226fbf ("fs/ntfs3: validate the EA value length in ntfs_read_ea()") Signed-off-by: Sasha Levin --- fs/ntfs3/xattr.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c index e246263aa3948..0bd1de7cf0362 100644 --- a/fs/ntfs3/xattr.c +++ b/fs/ntfs3/xattr.c @@ -167,6 +167,24 @@ static int ntfs_read_ea(struct ntfs_inode *ni, struct EA_FULL **ea, 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) + goto out1; continue; } -- 2.53.0