CVE-2026-74703: vhost-scsi: Validate T10 PI scatterlist counts

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

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

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

vhost-scsi: Validate T10 PI scatterlist counts

When T10 PI is negotiated, vhost-scsi splits protection bytes from
the data iterator before mapping the request scatterlists. A malformed
request can claim protection bytes that cover or exceed the full payload
length. The former leaves no data bytes to map, while the latter
underflows exp_data_len before advancing the iterator. Both cases can let
a zero data SGL count reach sg_alloc_table_chained(), which triggers
BUG_ON(!nents).

Reject protection lengths that cover or exceed the payload before
subtracting prot_bytes and advancing the iterator. Also propagate
negative errors from the protection SGL calculation before calling the
allocator, matching the data SGL path.

The Linux kernel CVE team has assigned CVE-2026-74703 to this issue.


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

	Issue introduced in 6.15 with commit bca939d5bcd00d6faea99c47eafd60bed573ef03 and fixed in 6.18.45 with commit 2417a498cf3fe64d06faf87e236eda98dd4f04e0
	Issue introduced in 6.15 with commit bca939d5bcd00d6faea99c47eafd60bed573ef03 and fixed in 7.1.9 with commit f8fe3f8d342da750dd10361bf66009fd3072926b
	Issue introduced in 6.15 with commit bca939d5bcd00d6faea99c47eafd60bed573ef03 and fixed in 7.2 with commit d876c493fc4b811941bfeb4c80beb2dfc4bf025e

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-2026-74703
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/vhost/scsi.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/2417a498cf3fe64d06faf87e236eda98dd4f04e0
	https://git.kernel.org/stable/c/f8fe3f8d342da750dd10361bf66009fd3072926b
	https://git.kernel.org/stable/c/d876c493fc4b811941bfeb4c80beb2dfc4bf025e