kernel/linux.git/net/smc, branch v5.10.268

net: smc: fix splice entry lifetime imbalance in smc_rx_splice

2026-08-23T12:16:29+00:00

commit 5d9686af2976741bbd79b150d1c9e60b81e7f12e upstream. smc_rx_splice() passes pages to splice_to_pipe() before taking the references that cover the lifetime of each splice entry. In the VM-backed RMB path, splice_to_pipe() may drop unqueued entries through smc_rx_spd_release(), while queued entries are released later via the pipe buffer callback. The old post-splice accounting also derives the number of queued VM pages from an offset mutated while building the descriptor, and a multi-page splice pairs one sock_hold() with multiple sock_put() calls. Take the page and socket references for every candidate entry before splice_to_pipe(), and drop the matching private state, page reference, and socket reference from smc_rx_spd_release() for entries that never get queued. This fixes a refcount imbalance that can underflow page refcounts and trigger a use-after-free. Fixes: 9014db202cb7 ("smc: add support for splice()") Cc: stable@vger.kernel.org Reported-by: Vega Co-developed-by: Xiao Liu Signed-off-by: Xiao Liu Signed-off-by: Daming Li Signed-off-by: Ren Wei Reviewed-by: Dust Li Reviewed-by: Sidraya Jayagond Link: https://patch.msgid.link/20260730145552.360287-2-enjou1224z@gmail.com Signed-off-by: Jakub Kicinski [ collapsed the multi-page get_page()/sock_hold() loop to a single get_page()/sock_hold() pair and dropped the trailing kfree() calls, as 5.15 lacks the multi-page pages[]/partial[]/priv[] arrays ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net/smc: rdma write inline if qp has sufficient inline space

2026-08-23T12:16:29+00:00

commit 793a7df63071eb09e5b88addf2a569d7bfd3c973 upstream. Rdma write with inline flag when sending small packages, whose length is shorter than the qp's max_inline_data, can help reducing latency. In my test environment, which are 2 VMs running on the same physical host and whose NICs(ConnectX-4Lx) are working on SR-IOV mode, qperf shows 0.5us-0.7us improvement in latency. Test command: server: smc_run taskset -c 1 qperf client: smc_run taskset -c 1 qperf -oo \ msg_size:1:2K:*2 -t 30 -vu tcp_lat The results shown below: msgsize before after 1B 11.2 us 10.6 us (-0.6 us) 2B 11.2 us 10.7 us (-0.5 us) 4B 11.3 us 10.7 us (-0.6 us) 8B 11.2 us 10.6 us (-0.6 us) 16B 11.3 us 10.7 us (-0.6 us) 32B 11.3 us 10.6 us (-0.7 us) 64B 11.2 us 11.2 us (0 us) 128B 11.2 us 11.2 us (0 us) 256B 11.2 us 11.2 us (0 us) 512B 11.4 us 11.3 us (-0.1 us) 1KB 11.4 us 11.5 us (0.1 us) 2KB 11.5 us 11.5 us (0 us) Signed-off-by: Guangguan Wang Reviewed-by: Tony Lu Tested-by: kernel test robot Acked-by: Karsten Graul Signed-off-by: Jakub Kicinski Stable-dep-of: 5d9686af2976 ("net: smc: fix splice entry lifetime imbalance in smc_rx_splice") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net/smc: reject CHID-0 ACCEPT that matches an empty ism_dev slot

2026-08-23T12:16:18+00:00

commit 277740023def559a4a2ddc3e8e784ee37a0f16a9 upstream. On the SMC-D client, slot 0 of ini->ism_dev[]/ini->ism_chid[] is reserved for an SMC-Dv1 device. smc_find_ism_v2_device_clnt() populates V2 entries starting at index 1, so when no V1 device is selected slot 0 is left in its kzalloc()'ed state with ism_dev[0] == NULL and ism_chid[0] == 0. smc_v2_determine_accepted_chid() then matches the peer's CHID against the array starting from index 0 using the CHID alone. A malicious peer replying to a SMC-Dv2-only proposal with d1.chid == 0 matches the empty slot, ini->ism_selected becomes 0, and the subsequent ism_dev[0]->lgr_lock dereference in smc_conn_create() faults at offsetof(struct smcd_dev, lgr_lock) == 0x68: BUG: KASAN: null-ptr-deref in _raw_spin_lock_bh+0x79/0xe0 Write of size 4 at addr 0000000000000068 by task exploit/144 Call Trace: _raw_spin_lock_bh smc_conn_create (net/smc/smc_core.c:1997) __smc_connect (net/smc/af_smc.c:1447) smc_connect (net/smc/af_smc.c:1720) __sys_connect __x64_sys_connect do_syscall_64 Require ism_dev[i] to be non-NULL before accepting a CHID match. Fixes: a7c9c5f4af7f ("net/smc: CLC accept / confirm V2") Reported-by: Weiming Shi Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Xiang Mei Link: https://patch.msgid.link/20260511062138.2839584-1-xmei5@asu.edu Signed-off-by: Paolo Abeni Signed-off-by: Andrey Troshin Signed-off-by: Greg Kroah-Hartman

net/smc: fix qentry overwrite for CONFIRM_LINK and ADD_LINK_CONT in smc_llc_event_handler()

2026-08-19T15:12:11+00:00

[ Upstream commit 976245094925bab9bc39366b2e9ab44ffcde61d0 ] The SMC_LLC_CONFIRM_LINK / SMC_LLC_ADD_LINK_CONT branch in smc_llc_event_handler() stores an incoming qentry into the local LLC flow without first checking whether a qentry is already pending. If a malicious or buggy peer sends a second CONFIRM_LINK or ADD_LINK_CONT request while a flow is active and flow->qentry is already set, smc_llc_flow_qentry_set() overwrites the pointer without freeing the previous allocation, leaking one kmalloc-96 object per spurious message. The sibling SMC_LLC_DELETE_LINK branch already has the correct !flow->qentry guard. Apply the same guard to the CONFIRM_LINK/ADD_LINK_CONT branch so that a duplicate message when qentry is already occupied falls through to break and is freed by the kfree(qentry) at the out: label, rather than silently leaking the existing allocation. The response direction (smc_llc_rx_response()) is unaffected: it already guards with flow->qentry at the equivalent site and drops duplicate responses correctly. Fixes: 0fb0b02bd6fd ("net/smc: adapt SMC client code to use the LLC flow") Signed-off-by: Mahanta Jambigi Reviewed-by: Hidayath Khan Reviewed-by: Sidraya Jayagond Reviewed-by: Dust Li Link: https://patch.msgid.link/20260729130153.970800-1-mjambigi@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/smc: fix socket use-after-free during link group termination

2026-08-19T15:12:08+00:00

commit f621d6ebeebb6374342571e4ddf45fdbc420f6cd upstream. __smc_lgr_terminate() drops conns_lock after finding a connection in lgr->conns_all, but before taking a reference on its socket. The connection is embedded in the socket, and its registration reference protects it only while the connection remains in the tree. A concurrent close can unregister the connection and drop that reference, freeing the socket before the termination worker reaches sock_hold(). The race is reachable when close overlaps link group termination. Local stress testing reproduced the use-after-free and KASAN reported: BUG: KASAN: slab-use-after-free in __smc_lgr_terminate.part.0 [smc] Write of size 4 by task kworker/3:3 Workqueue: events smc_lgr_terminate_work [smc] __smc_lgr_terminate.part.0 [smc] The socket was allocated by smc_create(), freed through slab_free_after_rcu_debug(), and was followed by: refcount_t: addition on 0; use-after-free. __smc_lgr_terminate.part.0 [smc] Take the socket reference while conns_lock still protects the tree entry. The unregister path then cannot drop the last reference until termination has finished using the socket. Fixes: 69318b5215f2 ("net/smc: improve abnormal termination locking") Cc: stable@vger.kernel.org Signed-off-by: Xuanqiang Luo Reviewed-by: Mahanta Jambigi Link: https://patch.msgid.link/20260723105454.87016-1-xuanqiang.luo@linux.dev Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket

2026-07-24T13:49:07+00:00

[ Upstream commit 9d160b35cc34a2ba8229d07651468a7848325135 ] smc_cdc_rx_handler() looks up the connection by token under the link group's conns_lock, drops the lock, and then dereferences conn and the smc_sock derived from it, ending in sock_hold(&smc->sk) inside smc_cdc_msg_recv(). No reference is held across the lock release. The only reference pinning the socket while the connection is discoverable in the link group is taken in smc_lgr_register_conn() (sock_hold) and dropped in __smc_lgr_unregister_conn() (sock_put), both under conns_lock. Once the handler drops conns_lock, a concurrent close() -> smc_release() -> smc_conn_free() -> smc_lgr_unregister_conn() can drop that reference and free the smc_sock, so the handler's later sock_hold() runs on freed memory: WARNING: lib/refcount.c:25 at refcount_warn_saturate Workqueue: rxe_wq do_work refcount_warn_saturate (lib/refcount.c:25) smc_cdc_msg_recv (net/smc/smc_cdc.c:430) smc_cdc_rx_handler (net/smc/smc_cdc.c:502) smc_wr_rx_tasklet_fn (net/smc/smc_wr.c:445) tasklet_action_common (kernel/softirq.c:938) handle_softirqs (kernel/softirq.c:622) Kernel panic - not syncing: panic_on_warn set Only SMC-R is affected. The SMC-D receive tasklet is stopped by tasklet_kill(&conn->rx_tsklet) in smc_conn_free() before the connection is unregistered, so it cannot run concurrently with the free. Take the socket reference while still holding conns_lock, so the registration reference can no longer be the last one, and drop it once the handler is done. Fixes: d7b0e37c1ac1 ("net/smc: restructure CDC message reception") Reported-by: Weiming Shi Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Xiang Mei Link: https://patch.msgid.link/20260630183227.2044998-1-xmei5@asu.edu Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

use less confusing names for iov_iter direction initializers

2026-06-19T11:21:45+00:00

[ Upstream commit de4eda9de2d957ef2d6a8365a01e26a435e958cb ] READ/WRITE proved to be actively confusing - the meanings are "data destination, as used with read(2)" and "data source, as used with write(2)", but people keep interpreting those as "we read data from it" and "we write data to it", i.e. exactly the wrong way. Call them ITER_DEST and ITER_SOURCE - at least that is harder to misinterpret... Signed-off-by: Al Viro Stable-dep-of: a4f0b001782b ("vsock/virtio: reset connection on receiving queue overflow") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net: Remove redundant if statements

2026-06-19T11:21:45+00:00

[ Upstream commit 1160dfa178eb848327e9dec39960a735f4dc1685 ] The 'if (dev)' statement already move into dev_{put , hold}, so remove redundant if statements. Signed-off-by: Yajun Deng Signed-off-by: David S. Miller Stable-dep-of: e196115ec330 ("netfilter: nf_queue: hold bridge skb->dev while queued") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net/smc: Do not re-initialize smc hashtables

2026-06-19T11:21:25+00:00

[ Upstream commit 9e4389b0038781f19f97895186ed941ff8ac1678 ] INIT_HLIST_HEAD(&smc_v*_hashinfo.ht) are called after smc_nl_init(), proto_register() and sock_register(). This can lead to smc_v*_hashinfo.ht being reset even though hash entries already exist and are being used, possibly resulting in a corrupted list. Remove unnecessary and dangerous re-initialisation of smc_v*_hashinfo.ht in smc_init(); it is implicitly initialised to zero anyhow. Add HLIST_HEAD_INIT to the definitions for clarity. Fixes: f16a7dd5cf27 ("smc: netlink interface for SMC sockets") Suggested-by: Halil Pasic Signed-off-by: Alexandra Winter Acked-by: Halil Pasic Reviewed-by: Mahanta Jambigi Link: https://patch.msgid.link/20260521145639.10317-1-wintera@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/smc: avoid early lgr access in smc_clc_wait_msg

2026-06-01T15:29:19+00:00

commit 5a8db80f721deee8e916c2cfdee78decda02ce4f upstream. A CLC decline can be received while the handshake is still in an early stage, before the connection has been associated with a link group. The decline handling in smc_clc_wait_msg() updates link-group level sync state for first-contact declines, but that state only exists after link group setup has completed. Guard the link-group update accordingly and keep the per-socket peer diagnosis handling unchanged. This preserves the existing sync_err handling for established link-group contexts and avoids touching link-group state before it is available. Fixes: 0cfdd8f92cac ("smc: connection and link group creation") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Ruijie Li Signed-off-by: Ren Wei Reviewed-by: Dust Li Link: https://patch.msgid.link/08c68a5c817acf198cce63d22517e232e8d60718.1776850759.git.ruijieli51@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman