CVE-2026-72149: dmaengine: tegra: Fix burst size calculation

CVE-2026-72149: dmaengine: tegra: Fix burst size calculation

[Greg Kroah-Hartman]

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

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

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

dmaengine: tegra: Fix burst size calculation

Currently, the Tegra GPC DMA hardware requires the transfer length to
be a multiple of the max burst size configured for the channel. When a
client requests a transfer where the length is not evenly divisible by
the configured max burst size, the DMA hangs with partial burst at
the end.

Fix this by reducing the burst size to the largest power-of-2 value
that evenly divides the transfer length. For example, a 40-byte
transfer with a 16-byte max burst will now use an 8-byte burst
(40 / 8 = 5 complete bursts) instead of causing a hang.

This issue was observed with the PL011 UART driver where TX DMA
transfers of arbitrary lengths were stuck.

The Linux kernel CVE team has assigned CVE-2026-72149 to this issue.


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

	Issue introduced in 5.19 with commit ee17028009d49fffed8cc963455d33b1fd3f1d08 and fixed in 6.1.178 with commit 735951baa311c66353405dcac39375dd66441db0
	Issue introduced in 5.19 with commit ee17028009d49fffed8cc963455d33b1fd3f1d08 and fixed in 6.6.145 with commit 8f0f5de1091119679d87f60dfb1acbff4b2a0ed3
	Issue introduced in 5.19 with commit ee17028009d49fffed8cc963455d33b1fd3f1d08 and fixed in 6.12.97 with commit a3b76b54e06d73166af4d1a284a0e0711889060c
	Issue introduced in 5.19 with commit ee17028009d49fffed8cc963455d33b1fd3f1d08 and fixed in 6.18.40 with commit 7926c1e4be86379945fb5f168888ac4d2aaf6c91
	Issue introduced in 5.19 with commit ee17028009d49fffed8cc963455d33b1fd3f1d08 and fixed in 7.1.5 with commit 6e37e9e230c7e848bd8e8cd4db15bb18bcf11ad1
	Issue introduced in 5.19 with commit ee17028009d49fffed8cc963455d33b1fd3f1d08 and fixed in 7.2-rc1 with commit 4651df83b6c796daead3447e8fd874322918ee4f

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-2026-72149
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/dma/tegra186-gpc-dma.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/735951baa311c66353405dcac39375dd66441db0
	https://git.kernel.org/stable/c/8f0f5de1091119679d87f60dfb1acbff4b2a0ed3
	https://git.kernel.org/stable/c/a3b76b54e06d73166af4d1a284a0e0711889060c
	https://git.kernel.org/stable/c/7926c1e4be86379945fb5f168888ac4d2aaf6c91
	https://git.kernel.org/stable/c/6e37e9e230c7e848bd8e8cd4db15bb18bcf11ad1
	https://git.kernel.org/stable/c/4651df83b6c796daead3447e8fd874322918ee4f