xfs: handle NULL b_addr in xfs_buf_free

Answer in brief

CVE-2026-74728 records a Unknown severity vulnerability in xfs: handle NULL b_addr in xfs_buf_free. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 22, 2026Updated Aug 22, 2026Source checked Aug 22, 2026First seen by HOL Aug 22, 2026Material review Aug 22, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=5076a6040ca1613e616d84aecfaac5f932db84e0 <ccf6738adcafa5ddbddc4e71b45d8a51b86643c7 \|\| >=5076a6040ca1613e616d84aecfaac5f932db84e0 <3aa0c1d23ee1b9d9b340fb2f4736536e1408d706 \|\| >=5076a6040ca1613e616d84aecfaac5f932db84e0 <d852729c5f4f830fbe7413df032e29459b3daf83	ccf6738adcafa5ddbddc4e71b45d8a51b86643c7, 3aa0c1d23ee1b9d9b340fb2f4736536e1408d706, d852729c5f4f830fbe7413df032e29459b3daf83
Linux/Linuxgeneric	6.9	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to ccf6738adcafa5ddbddc4e71b45d8a51b86643c7 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 22, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: xfs: handle NULL b_addr in xfs_buf_free When xfs_buf_alloc_backing_mem() fails, xfs_buf_free() is called with bp->b_addr still NULL. The code falls through to the folio_put path which calls virt_to_folio(NULL), dereferencing an invalid address and causing a kernel crash. Call Trace: xfs_buf_free+0x25f/0x510 xfs_buf_alloc+0xc98/0x19b0 xfs_buf_find_insert+0x55/0x14d0 xfs_buf_get_map+0x122b/0x17c0 xfbtree_init_leaf_block+0x11c/0x4a0 xfbtree_init+0x1bb/0x460 xrep_rmap_setup_scan+0x100/0x1f0 xrep_rmapbt+0x41/0xc0 Fix this by skipping folio_put() when bp->b_addr is NULL.

Quoted source text, attributed separately from HOL analysis.