kernel/linux.git/drivers/dibs/dibs_loopback.c, branch v6.18.48

net/dibs: Correct freeing of dmb_clientid_arr

2026-08-19T16:18:17+00:00

commit 9e6869be49064915edb6c8776b27c376cfdb0df5 upstream. A dibs device interrupt handler can be active after dibs_dev_del() and may still access dmb_clientid_arr. (UAF) In case of a failure in dibs_dev_add() being called by dibs_lo_dev_probe() dmb_clientid_arr is freed twice (double free). Free dmb_clientid_arr in dibs_dev_release() after last reference is gone. Note that allocating in dibs_dev_add() instead of dibs_dev_alloc() is ok for now, because no dmbs can be registered before dibs_dev_add(). Fixes: cc21191b584c ("dibs: Move data path to dibs layer") Cc: stable@vger.kernel.org Co-developed-by: Hidayath Khan Signed-off-by: Hidayath Khan Signed-off-by: Alexandra Winter Reviewed-by: Dust Li Link: https://patch.msgid.link/20260810111432.2334900-1-wintera@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

dibs: fix use-after-free of dmb_node in loopback attach/detach/unregister

2026-08-09T18:25:12+00:00

commit a10ea943356b9d70c5616a0a06f6fa97cfdaccb1 upstream. dibs_lo_attach_dmb(), dibs_lo_detach_dmb() and dibs_lo_unregister_dmb() look up the dmb_node under dmb_ht_lock, drop the lock and only then operate on the node's refcount. Nothing keeps the node alive across that window: __dibs_lo_unregister_dmb() removes the node from the hash table under the write lock and immediately frees it. A concurrent final put can therefore free the node between the lookup and the refcount operation: CPU0 (attach) CPU1 (owner unregisters) read_lock_bh(&dmb_ht_lock) find dmb_node (refcnt == 1) read_unlock_bh(&dmb_ht_lock) refcount_dec_and_test() 1 -> 0 write_lock_bh(&dmb_ht_lock) hash_del(&dmb_node->list) write_unlock_bh(&dmb_ht_lock) kfree(dmb_node) refcount_inc_not_zero(&dmb_node->refcnt) <-- use-after-free The same window exists for the refcount_dec_and_test() calls in the detach and unregister paths. Close the race structurally by making hash table membership and the refcount transitions atomic with respect to each other: - Perform the final refcount_dec_and_test() and hash_del() in a single dmb_ht_lock write-side critical section, in both the unregister and the detach path. Freeing the node still happens after the lock is dropped, which is safe because a node whose refcount reached zero has left the hash table and can no longer be found. - This establishes the invariant that any node found in the hash table holds at least one reference, and that the final reference can only be dropped under the write lock. dibs_lo_attach_dmb() can thus take its reference with a plain refcount_inc() while still holding the read lock; refcount_inc_not_zero() is no longer needed. __dibs_lo_unregister_dmb() no longer touches the hash table and is renamed to dibs_lo_free_dmb() accordingly. Note: commit cc21191b584c ("dibs: Move data path to dibs layer") moved the code to its current location; the race was introduced earlier by commit c3a910f2380f ("net/smc: implement DMB-merged operations of loopback-ism"). Tested SMC-D via ISM and dibs loopback. Cc: stable@vger.kernel.org Fixes: c3a910f2380f ("net/smc: implement DMB-merged operations of loopback-ism") Reported-by: Rahul Chandelkar Signed-off-by: Hidayath Khan Reviewed-by: Alexandra Winter Link: https://patch.msgid.link/20260727093530.968834-1-hidayath@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

dibs: loopback: validate offset and size in move_data()

2026-07-24T14:17:16+00:00

commit 78237e3c0720fcc6eb9b87e90fd70f63eeca886f upstream. The loopback move_data() performs a memcpy into the registered DMB without checking whether offset + size exceeds the DMB length. Unlike real ISM hardware, which enforces memory region bounds natively, the software loopback has no such protection. A peer-supplied out-of-bounds offset or oversized write would result in an OOB write past the allocated kernel buffer. Add an explicit bounds check before the memcpy to reject such requests with -EINVAL. Fixes: f7a22071dbf3 ("net/smc: implement DMB-related operations of loopback-ism") Cc: stable@vger.kernel.org Reported-by: Federico Kirschbaum Signed-off-by: Dust Li Reported-by: Baul Lee Link: https://patch.msgid.link/20260707074318.1448662-1-dust.li@linux.alibaba.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2025-09-25T18:00:59+00:00

Cross-merge networking fixes after downstream PR (net-6.17-rc8). Conflicts: drivers/net/can/spi/hi311x.c 6b6968084721 ("can: hi311x: fix null pointer dereference when resuming from sleep before interface was enabled") 27ce71e1ce81 ("net: WQ_PERCPU added to alloc_workqueue users") https://lore.kernel.org/72ce7599-1b5b-464a-a5de-228ff9724701@kernel.org net/smc/smc_loopback.c drivers/dibs/dibs_loopback.c a35c04de2565 ("net/smc: fix warning in smc_rx_splice() when calling get_page()") cc21191b584c ("dibs: Move data path to dibs layer") https://lore.kernel.org/74368a5c-48ac-4f8e-a198-40ec1ed3cf5f@kernel.org Adjacent changes: drivers/net/dsa/lantiq/lantiq_gswip.c c0054b25e2f1 ("net: dsa: lantiq_gswip: move gswip_add_single_port_br() call to port_setup()") 7a1eaef0a791 ("net: dsa: lantiq_gswip: support model-specific mac_select_pcs()") Signed-off-by: Jakub Kicinski

dibs: Move data path to dibs layer

2025-09-23T09:13:22+00:00

Use struct dibs_dmb instead of struct smc_dmb and move the corresponding client tables to dibs_dev. Leave driver specific implementation details like sba in the device drivers. Register and unregister dmbs via dibs_dev_ops. A dmb is dedicated to a single client, but a dibs device can have dmbs for more than one client. Trigger dibs clients via dibs_client_ops->handle_irq(), when data is received into a dmb. For dibs_loopback replace scheduling an smcd receive tasklet with calling dibs_client_ops->handle_irq(). For loopback devices attach_dmb(), detach_dmb() and move_data() need to access the dmb tables, so move those to dibs_dev_ops in this patch as well. Remove remaining definitions of smc_loopback as they are no longer required, now that everything is in dibs_loopback. Note that struct ism_client and struct ism_dev are still required in smc until a follow-on patch moves event handling to dibs. (Loopback does not use events). Signed-off-by: Alexandra Winter Link: https://patch.msgid.link/20250918110500.1731261-14-wintera@linux.ibm.com Signed-off-by: Paolo Abeni

dibs: Move query_remote_gid() to dibs_dev_ops

2025-09-23T09:13:22+00:00

Provide the dibs_dev_ops->query_remote_gid() in ism and dibs_loopback dibs_devices. And call it in smc dibs_client. Reviewed-by: Julian Ruess Signed-off-by: Alexandra Winter Link: https://patch.msgid.link/20250918110500.1731261-13-wintera@linux.ibm.com Signed-off-by: Paolo Abeni

dibs: Local gid for dibs devices

2025-09-23T09:13:22+00:00

Define a uuid_t GID attribute to identify a dibs device. SMC uses 64 Bit and 128 Bit Global Identifiers (GIDs) per device, that need to be sent via the SMC protocol. Because the smc code uses integers, network endianness and host endianness need to be considered. Avoid this in the dibs layer by using uuid_t byte arrays. Future patches could change SMC to use uuid_t. For now conversion helper functions are introduced. ISM devices provide 64 Bit GIDs. Map them to dibs uuid_t GIDs like this: _________________________________________ | 64 Bit ISM-vPCI GID | 00000000_00000000 | ----------------------------------------- If interpreted as UUID [1], this would be interpreted as the UIID variant, that is reserved for NCS backward compatibility. So it will not collide with UUIDs that were generated according to the standard. smc_loopback already uses version 4 UUIDs as 128 Bit GIDs, move that to dibs loopback. A temporary change to smc_lo_query_rgid() is required, that will be moved to dibs_loopback with a follow-on patch. Provide gid of a dibs device as sysfs read-only attribute. Link: https://datatracker.ietf.org/doc/html/rfc4122 [1] Signed-off-by: Alexandra Winter Reviewed-by: Julian Ruess Reviewed-by: Mahanta Jambigi Link: https://patch.msgid.link/20250918110500.1731261-11-wintera@linux.ibm.com Signed-off-by: Paolo Abeni

dibs: Move struct device to dibs_dev

2025-09-23T09:13:22+00:00

Move struct device from ism_dev and smc_lo_dev to dibs_dev, and define a corresponding release function. Free ism_dev in ism_remove() and smc_lo_dev in smc_lo_dev_remove(). Replace smcd->ops->get_dev(smcd) by using dibs->dev directly. An alternative design would be to embed dibs_dev as a field in ism_dev and do the same for other dibs device driver specific structs. However that would have the disadvantage that each dibs device driver needs to allocate dibs_dev and each dibs device driver needs a different device release function. The advantage would be that ism_dev and other device driver specific structs would be covered by device reference counts. Signed-off-by: Julian Ruess Co-developed-by: Alexandra Winter Signed-off-by: Alexandra Winter Reviewed-by: Mahanta Jambigi Link: https://patch.msgid.link/20250918110500.1731261-9-wintera@linux.ibm.com Signed-off-by: Paolo Abeni

dibs: Define dibs_client_ops and dibs_dev_ops

2025-09-23T09:13:22+00:00

Move the device add() and remove() functions from ism_client to dibs_client_ops and call add_dev()/del_dev() for ism devices and dibs_loopback devices. dibs_client_ops->add_dev() = smcd_register_dev() for the smc_dibs_client. This is the first step to handle ism and loopback devices alike (as dibs devices) in the smc dibs client. Define dibs_dev->ops and move smcd_ops->get_chid to dibs_dev_ops->get_fabric_id() for ism and loopback devices. See below for why this needs to be in the same patch as dibs_client_ops->add_dev(). The following changes contain intermediate steps, that will be obsoleted by follow-on patches, once more functionality has been moved to dibs: Use different smcd_ops and max_dmbs for ism and loopback. Follow-on patches will change SMC-D to directly use dibs_ops instead of smcd_ops. In smcd_register_dev() it is now necessary to identify a dibs_loopback device before smcd_dev and smcd_ops->get_chid() are available. So provide dibs_dev_ops->get_fabric_id() in this patch and evaluate it in smc_ism_is_loopback(). Call smc_loopback_init() in smcd_register_dev() and call smc_loopback_exit() in smcd_unregister_dev() to handle the functionality that is still in smc_loopback. Follow-on patches will move all smc_loopback code to dibs_loopback. In smcd_[un]register_dev() use only ism device name, this will be replaced by dibs device name by a follow-on patch. End of changes with intermediate parts. Allocate an smcd event workqueue for all dibs devices, although dibs_loopback does not generate events. Use kernel memory instead of devres memory for smcd_dev and smcd->conn. Since commit a72178cfe855 ("net/smc: Fix dependency of SMC on ISM") an ism device and its driver can have a longer lifetime than the smc module, so smc should not rely on devres to free its resources [1]. It is now the responsibility of the smc client to free smcd and smcd->conn for all dibs devices, ism devices as well as loopback. Call client->ops->del_dev() for all existing dibs devices in dibs_unregister_client(), so all device related structures can be freed in the client. When dibs_unregister_client() is called in the context of smc_exit() or smc_core_reboot_event(), these functions have already called smc_lgrs_shutdown() which calls smc_smcd_terminate_all(smcd) and sets going_away. This is done a second time in smcd_unregister_dev(). This is analogous to how smcr is handled in these functions, by calling first smc_lgrs_shutdown() and then smc_ib_unregister_client() > smc_ib_remove_dev(), so leave it that way. It may be worth investigating, whether smc_lgrs_shutdown() is still required or useful. Remove CONFIG_SMC_LO. CONFIG_DIBS_LO now controls whether a dibs loopback device exists or not. Link: https://www.kernel.org/doc/Documentation/driver-model/devres.txt [1] Signed-off-by: Alexandra Winter Reviewed-by: Mahanta Jambigi Link: https://patch.msgid.link/20250918110500.1731261-8-wintera@linux.ibm.com Signed-off-by: Paolo Abeni

dibs: Define dibs loopback

2025-09-23T09:13:21+00:00

The first stage of loopback-ism was implemented as part of the SMC module [1]. Now that we have the dibs layer, provide access to a dibs_loopback device to all dibs clients. This is the first step of moving loopback-ism from net/smc/smc_loopback.* to drivers/dibs/dibs_loopback.*. One global structure lo_dev is allocated and added to the dibs devices. Follow-on patches will move functionality. Same as smc_loopback, dibs_loopback is provided by a config option. Note that there is no way to dynamically add or remove the loopback device. That could be a future improvement. When moving code to drivers/dibs, replace ism_ prefix with dibs_ prefix. As this is mostly a move of existing code, copyright and authors are unchanged. Link: https://lore.kernel.org/lkml/20240428060738.60843-1-guwen@linux.alibaba.com/ [1] Signed-off-by: Alexandra Winter Link: https://patch.msgid.link/20250918110500.1731261-7-wintera@linux.ibm.com Signed-off-by: Paolo Abeni