Bug 2555180 (CVE-2026-98724)

Summary: CVE-2026-98724 kernel: nvmet: pci-epf: reject too-short SGL segments
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Non-Volatile Memory Express (NVMe) target PCI endpoint function driver. When processing a Scatter-Gather List (SGL) segment whose length is shorter than a single descriptor, the system fails to properly validate the segment size. A connected host can exploit this vulnerability by submitting a malformed SGL segment, triggering an out-of-bounds memory read. This issue primarily allows an attacker to cause a kernel crash leading to a Denial of Service (DoS), or potentially expose sensitive memory contents.
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Description OSIDB Bzimport 2026-10-18 15:59:13 UTC 
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.
Comment 1 Mauro Matteo Cascella 2026-10-22 18:37:44 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98724.mbox