CVE-2026-98724: nvmet: pci-epf: reject too-short SGL segments

CVE-2026-98724: nvmet: pci-epf: reject too-short SGL segments

[Greg Kroah-Hartman]

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

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

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

nvmet: pci-epf: reject too-short SGL segments

The host controls an SGL segment's length. A nonzero length smaller than
one SGL descriptor makes nr_descs zero, so
nvmet_pci_epf_get_sgl_segment() reads the type byte of sgls[-1] outside
the allocated buffer. If that byte contains a segment descriptor type,
the function also copies the preceding 16 bytes and returns a negative
descriptor count.

The read was reproduced in 3/3 KASAN boots with only the host transfer
mocked by a KUnit test:

  BUG: KASAN: slab-out-of-bounds in nvmet_pci_epf_get_sgl_segment
  Read of size 1 by task kunit_try_catch
  Call Trace:
   nvmet_pci_epf_get_sgl_segment
   nvmet_pci_epf_short_sgl_test
  Kernel panic - not syncing: KASAN: panic_on_warn set ...

Reject segments that cannot hold one descriptor before allocating or
transferring their contents.

The Linux kernel CVE team has assigned CVE-2026-98724 to this issue.


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

	Issue introduced in 6.14 with commit 0faa0fe6f90ea59b10d1b0f15ce0eb0c18eff186 and fixed in 6.18.56 with commit 2423a05dd0f21330c47ce0ae1cb54a8b0be821e2
	Issue introduced in 6.14 with commit 0faa0fe6f90ea59b10d1b0f15ce0eb0c18eff186 and fixed in 7.2.10 with commit 472df1d103dbe3e9d09156f0667e36180e912c46
	Issue introduced in 6.14 with commit 0faa0fe6f90ea59b10d1b0f15ce0eb0c18eff186 and fixed in 7.3-rc6 with commit 5d5fbfbbacd1efb13a9bf91317d4fde859ede4b9

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-2026-98724
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/nvme/target/pci-epf.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/2423a05dd0f21330c47ce0ae1cb54a8b0be821e2
	https://git.kernel.org/stable/c/472df1d103dbe3e9d09156f0667e36180e912c46
	https://git.kernel.org/stable/c/5d5fbfbbacd1efb13a9bf91317d4fde859ede4b9