Message-ID: <2025120938-CVE-2023-53778-ee4d@gregkh>
Date: Tue,  9 Dec 2025 09:01:59 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53778: accel/qaic: Clean up integer overflow checking in map_user_pages()

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

accel/qaic: Clean up integer overflow checking in map_user_pages()

The encode_dma() function has some validation on in_trans->size but it
would be more clear to move those checks to find_and_map_user_pages().

The encode_dma() had two checks:

	if (in_trans->addr + in_trans->size < in_trans->addr || !in_trans->size)
		return -EINVAL;

The in_trans->addr variable is the starting address.  The in_trans->size
variable is the total size of the transfer.  The transfer can occur in
parts and the resources->xferred_dma_size tracks how many bytes we have
already transferred.

This patch introduces a new variable "remaining" which represents the
amount we want to transfer (in_trans->size) minus the amount we have
already transferred (resources->xferred_dma_size).

I have modified the check for if in_trans->size is zero to instead check
if in_trans->size is less than resources->xferred_dma_size.  If we have
already transferred more bytes than in_trans->size then there are negative
bytes remaining which doesn't make sense.  If there are zero bytes
remaining to be copied, just return success.

The check in encode_dma() checked that "addr + size" could not overflow
and barring a driver bug that should work, but it's easier to check if
we do this in parts.  First check that "in_trans->addr +
resources->xferred_dma_size" is safe.  Then check that "xfer_start_addr +
remaining" is safe.

My final concern was that we are dealing with u64 values but on 32bit
systems the kmalloc() function will truncate the sizes to 32 bits.  So
I calculated "total = in_trans->size + offset_in_page(xfer_start_addr);"
and returned -EINVAL if it were >= SIZE_MAX.  This will not affect 64bit
systems.

The Linux kernel CVE team has assigned CVE-2023-53778 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.4 with commit 129776ac2e38231fa9c02ce20e116c99de291666 and fixed in 6.4.12 with commit d410a96e5cb8c1ec7049c83f2edcd8bbfaf5d9b3
	Issue introduced in 6.4 with commit 129776ac2e38231fa9c02ce20e116c99de291666 and fixed in 6.5 with commit 96d3c1cadedb6ae2e8965e19cd12caa244afbd9c

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-2023-53778
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:
	drivers/accel/qaic/qaic_control.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/d410a96e5cb8c1ec7049c83f2edcd8bbfaf5d9b3
	https://git.kernel.org/stable/c/96d3c1cadedb6ae2e8965e19cd12caa244afbd9c

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