Subject: CVE-2023-52910: iommu/iova: Fix alloc iova overflows issue

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

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

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

iommu/iova: Fix alloc iova overflows issue

In __alloc_and_insert_iova_range, there is an issue that retry_pfn
overflows. The value of iovad->anchor.pfn_hi is ~0UL, then when
iovad->cached_node is iovad->anchor, curr_iova->pfn_hi + 1 will
overflow. As a result, if the retry logic is executed, low_pfn is
updated to 0, and then new_pfn < low_pfn returns false to make the
allocation successful.

This issue occurs in the following two situations:
1. The first iova size exceeds the domain size. When initializing
iova domain, iovad->cached_node is assigned as iovad->anchor. For
example, the iova domain size is 10M, start_pfn is 0x1_F000_0000,
and the iova size allocated for the first time is 11M. The
following is the log information, new->pfn_lo is smaller than
iovad->cached_node.

Example log as follows:
[  223.798112][T1705487] sh: [name:iova&]__alloc_and_insert_iova_range
start_pfn:0x1f0000,retry_pfn:0x0,size:0xb00,limit_pfn:0x1f0a00
[  223.799590][T1705487] sh: [name:iova&]__alloc_and_insert_iova_range
success start_pfn:0x1f0000,new->pfn_lo:0x1efe00,new->pfn_hi:0x1f08ff

2. The node with the largest iova->pfn_lo value in the iova domain
is deleted, iovad->cached_node will be updated to iovad->anchor,
and then the alloc iova size exceeds the maximum iova size that can
be allocated in the domain.

After judging that retry_pfn is less than limit_pfn, call retry_pfn+1
to fix the overflow issue.

The Linux kernel CVE team has assigned CVE-2023-52910 to this issue.

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

	Issue introduced in 5.11 with commit 4e89dce72521 and fixed in 5.15.89 with commit c929a230c844
	Issue introduced in 5.11 with commit 4e89dce72521 and fixed in 6.1.7 with commit 61cbf790e732
	Issue introduced in 5.11 with commit 4e89dce72521 and fixed in 6.2 with commit dcdb3ba7e2a8

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-2023-52910
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/iommu/iova.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/c929a230c84441e400c32e7b7b4ab763711fb63e
	https://git.kernel.org/stable/c/61cbf790e7329ed78877560be7136f0b911bba7f
	https://git.kernel.org/stable/c/dcdb3ba7e2a8caae7bfefd603bc22fd0ce9a389c