From: Michael Liang <mliang@purestorage.com> stable inclusion from stable-v6.6.128 commit 7daf279c674d515fb22a727a7bbc92aeb35c5442 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8792 CVE: CVE-2026-43278 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit fb8a6c18fb9a6561f7a15b58b272442b77a242dd ] 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. Signed-off-by: Michael Liang <mliang@purestorage.com> Reviewed-by: Mohamed Khalfella <mkhalfella@purestorage.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- drivers/md/dm-rq.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 499f8cc8a39f..5bcf020df856 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -109,14 +109,21 @@ static void end_clone_bio(struct bio *clone) */ tio->completed += nr_bytes; + if (!is_last) + return; + /* + * At this moment we know this is the last bio of the cloned request, + * and all cloned bios have been released, so reset the clone request's + * bio pointer to avoid double free. + */ + tio->clone->bio = NULL; + exit: /* * Update the original request. * Do not use blk_mq_end_request() here, because it may complete * the original request before the clone, and break the ordering. */ - if (is_last) - exit: - blk_update_request(tio->orig, BLK_STS_OK, tio->completed); + blk_update_request(tio->orig, BLK_STS_OK, tio->completed); } static struct dm_rq_target_io *tio_from_request(struct request *rq) -- 2.52.0