From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 077B3585970 for ; Fri, 11 Sep 2026 20:00:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156817; cv=none; b=REYwcouTkTougbHbq3obdroNLOY136aelL+wPSYcNsMHHcA/Z8WoR0MdcUBVC4TrTiBeKMCs+tDT26pOcZEyOU2/aaGaHJ1mnJRvSEsy47aceLI2D7d9IumNncDtAQ1B0PgVt9Hg7iK6jaE6JvYukLahA5YfWPXwCMpvBBwz5/g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156817; c=relaxed/simple; bh=pOeuvW/kkm7+7B56da7eZl7F3/LZFIwRXb6jxc9cL7I=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ENzESDlNkof1+ZPlcpkaWXZc2f3aNJuSnJVsTbgBd3+zQVE5xN/qUqUJsJwPvk7Q9lrp4fHMpVgRwDrCTcbYUZBRoxQKRWNETX2gDalxq6aaKJWtMnKo/KIvGkz/tWEkc6xEYWrGuYh87sWIlJoO9oNVrDhEj8mSlnsisCppeIY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BHr1X/Fo; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="BHr1X/Fo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52B6C1F00893; Fri, 11 Sep 2026 20:00:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156806; bh=KnFsKd7YQfCimihCmu05/9yjbSkYCWKCE+FqKtgPASg=; h=From:To:Cc:Subject:Date:Reply-To; b=BHr1X/Fo/LPYIBYxabprhdPcYCUmGhmc9VSnFal5MiQWorQ5ib5TabekEwuPgwExX nQF30bMZJ66DRuvItzbmgJZMvTd4TLOnzPzN3J9tw5L5cFGMMpaDZSC6Badl4GNBbw qCEgVtaTcgKGEEBvr1zRuAX/di+jdevxfe1mFLfc= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89640: cifs: fix loff_t underflow in cifs_remap_file_range() when len == 0 Date: Fri, 11 Sep 2026 21:45:29 +0200 Message-ID: <2026091141-CVE-2026-89640-ed71@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2860; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=nPsJRDVyBeO07h7293LOdKhOJN4OnntMbEY8GrClbCM=; b=kA0DAAIRMUfUDdst+ykByyZiAGqkWXWhQIemB9doYqKYataKxW2n/1lG4EiWBmGyKdlDxrxMH 4hdBAARAgAdFiEE9LYMxb94wiFKMT3LMUfUDdst+ykFAmqkWXUACgkQMUfUDdst+ylcpACfabIy hMQmrNvWdxuug2xo9wLJZwoAn3RW4rbhyd3UYXkoLhkmyRLLbrM9 X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: cifs: fix loff_t underflow in cifs_remap_file_range() when len == 0 With len == 0 (clone to EOF), the effective length is computed as: len = src_inode->i_size - off; If off > i_size, this is a negative loff_t, corrupting the ByteCount in the FSCTL_DUPLICATE_EXTENTS_TO_FILE request and inverting the range in filemap_write_and_wait_range(). The existing off >= i_size check fires only after the ioctl has already been sent. Snapshot i_size_read() once for both the bounds check and the length calculation, eliminating the TOCTOU and 32-bit torn-read risk. Reject off > src_size with -EINVAL. Treat off == src_size as a no-op, consistent with __generic_remap_file_range_prep(). The Linux kernel CVE team has assigned CVE-2026-89640 to this issue. Affected and fixed versions =========================== Issue introduced in 4.5 with commit 04b38d601239b4d9be641b412cf4b7456a041c67 and fixed in 6.12.109 with commit b098f5e5858797827666e6cd73033f52fc39b5f6 Issue introduced in 4.5 with commit 04b38d601239b4d9be641b412cf4b7456a041c67 and fixed in 6.18.50 with commit c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028 Issue introduced in 4.5 with commit 04b38d601239b4d9be641b412cf4b7456a041c67 and fixed in 7.2.4 with commit b057ca17b656345d04669cb87f2aff9b31d873db Issue introduced in 4.5 with commit 04b38d601239b4d9be641b412cf4b7456a041c67 and fixed in 7.3-rc1 with commit 6c322f5cf7476ded7a9a20f7be72462065a03c68 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-89640 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: fs/smb/client/cifsfs.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/b098f5e5858797827666e6cd73033f52fc39b5f6 https://git.kernel.org/stable/c/c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028 https://git.kernel.org/stable/c/b057ca17b656345d04669cb87f2aff9b31d873db https://git.kernel.org/stable/c/6c322f5cf7476ded7a9a20f7be72462065a03c68