CVE-2026-64232
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk38th percentile - higher than 38% of all known CVEs
Summary
A vulnerability was found in the Linux kernel's blk_insert_cloned_request() function, which did not recompute the nr_integrity_segments for cloned requests. This can trigger a BUG_ON() during segment mapping when the bottom queue has stricter segmentation settings than the top queue.
Risk Assessment
The risk involves potential kernel panics in stacked block device setups like dm-multipath with nvme-rdma, which can disrupt critical services and cause data loss.
Recommendation
Immediately update the Linux kernel to a version containing the fix that adds recomputation of nr_integrity_segments in blk_insert_cloned_request(). Check your distribution for the available patch.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: block: recompute nr_integrity_segments in blk_insert_cloned_request blk_insert_cloned_request() already recomputes nr_phys_segments against the bottom queue, because "the queue settings related to segment counting may differ from the original queue." The exact same reasoning applies to integrity segments: a stacked driver's underlying queue can have tighter virt_boundary_mask, seg_boundary_mask, or max_segment_size than the top queue, in which case blk_rq_count_integrity_sg() against the bottom queue produces a different count than the cached rq->nr_integrity_segments inherited from the source request by blk_rq_prep_clone(). When the cached count is lower than the bottom queue's actual count, blk_rq_map_integrity_sg() trips BUG_ON(segments > rq->nr_integrity_segments); on dispatch. The same families of stacked setups that motivated the existing nr_phys_segments recompute -- dm-multipath fanning out to nvme-rdma in particular -- can produce this. Mirror the nr_phys_segments handling: when the request carries integrity, recompute nr_integrity_segments against the bottom queue and reject the request if it exceeds the bottom queue's max_integrity_segments. blk_rq_count_integrity_sg() and queue_max_integrity_segments() are both already available via <linux/blk-integrity.h>, which blk-mq.c includes. This closes a latent gap in the stacking contract and brings the integrity-segment accounting in line with the existing phys-segment accounting.