Subject: CVE-2023-52517: spi: sun6i: fix race between DMA RX transfer completion and RX FIFO drain

From: Greg Kroah-Hartman <[email-masked]>

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

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

spi: sun6i: fix race between DMA RX transfer completion and RX FIFO drain

Previously the transfer complete IRQ immediately drained to RX FIFO to
read any data remaining in FIFO to the RX buffer. This behaviour is
correct when dealing with SPI in interrupt mode. However in DMA mode the
transfer complete interrupt still fires as soon as all bytes to be
transferred have been stored in the FIFO. At that point data in the FIFO
still needs to be picked up by the DMA engine. Thus the drain procedure
and DMA engine end up racing to read from RX FIFO, corrupting any data
read. Additionally the RX buffer pointer is never adjusted according to
DMA progress in DMA mode, thus calling the RX FIFO drain procedure in DMA
mode is a bug.
Fix corruptions in DMA RX mode by draining RX FIFO only in interrupt mode.
Also wait for completion of RX DMA when in DMA mode before returning to
ensure all data has been copied to the supplied memory buffer.

The Linux kernel CVE team has assigned CVE-2023-52517 to this issue.

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

	Fixed in 5.15.134 with commit bd1ec7f9983b
	Fixed in 6.1.56 with commit 36b29974a7ad
	Fixed in 6.5.6 with commit 4e149d524678
	Fixed in 6.6 with commit 1f11f4202caf

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-2023-52517
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/spi/spi-sun6i.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/bd1ec7f9983b5cd3c77e0f7cda3fa8aed041af2f
	https://git.kernel.org/stable/c/36b29974a7ad2ff604c24ad348f940506c7b1209
	https://git.kernel.org/stable/c/4e149d524678431638ff378ef6025e4e89b71097
	https://git.kernel.org/stable/c/1f11f4202caf5710204d334fe63392052783876d