Linux Kernel DM: Double-Free in request-clone bios fixed
CVE-2026-43278 Published on May 6, 2026
dm: clear cloned request bio pointer when last clone bio completes
In the Linux kernel, the following vulnerability has been resolved:
dm: clear cloned request bio pointer when last clone bio completes
Stale rq->bio values have been observed to cause double-initialization of
cloned bios in request-based device-mapper targets, leading to
use-after-free and double-free scenarios.
One such case occurs when using dm-multipath on top of a PCIe NVMe
namespace, where cloned request bios are freed during
blk_complete_request(), but rq->bio is left intact. Subsequent clone
teardown then attempts to free the same bios again via
blk_rq_unprep_clone().
The resulting double-free path looks like:
nvme_pci_complete_batch()
nvme_complete_batch()
blk_mq_end_request_batch()
blk_complete_request() // called on a DM clone request
bio_endio() // first free of all clone bios
...
rq->end_io() // end_clone_request()
dm_complete_request(tio->orig)
dm_softirq_done()
dm_done()
dm_end_request()
blk_rq_unprep_clone() // second free of clone bios
Fix this by clearing the clone request's bio pointer when the last cloned
bio completes, ensuring that later teardown paths do not attempt to free
already-released bios.
Products Associated with CVE-2026-43278
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Affected Versions
Linux:- Version ab3e1d3bbab9e973aeb4dd4603251578658a47ff and below 8d9ddad561136f7e6a9346767bf97b4d79e38e67 is affected.
- Version ab3e1d3bbab9e973aeb4dd4603251578658a47ff and below 7daf279c674d515fb22a727a7bbc92aeb35c5442 is affected.
- Version ab3e1d3bbab9e973aeb4dd4603251578658a47ff and below e2e738e8dfbbf83bd2bae0467ec4420cc52da42a is affected.
- Version ab3e1d3bbab9e973aeb4dd4603251578658a47ff and below b1c1a2637ebd675aa2d71fee8c70da8791d73850 is affected.
- Version ab3e1d3bbab9e973aeb4dd4603251578658a47ff and below 83d72091804600ead96dc9e9f518ea56cb4942f6 is affected.
- Version ab3e1d3bbab9e973aeb4dd4603251578658a47ff and below fb8a6c18fb9a6561f7a15b58b272442b77a242dd is affected.
- Version 6.1 is affected.
- Before 6.1 is unaffected.
- Version 6.1.165, <= 6.1.* is unaffected.
- Version 6.6.128, <= 6.6.* is unaffected.
- Version 6.12.75, <= 6.12.* is unaffected.
- Version 6.18.16, <= 6.18.* is unaffected.
- Version 6.19.6, <= 6.19.* is unaffected.
- Version 7.0, <= * is unaffected.