kernel/git/stable/linux-stable.git/net/smc, branch linux-rolling-stable

net/smc: release the internal TCP sock on IPPROTO_SMC socket creation failure

2026-09-14T11:41:08+00:00

[ Upstream commit cec261b0b4c5c0b044165303198d10ffcdf3414c ] IPPROTO_SMC sockets create an internal TCP sock ("clcsock") from the proto->init hook. When socket creation fails after proto->init has run - e.g. a cgroup BPF program attached to BPF_CGROUP_INET_SOCK_CREATE denies the socket - sk_common_release() only invokes sk_prot->destroy if it is set, but neither smc_inet_prot nor smc_inet6_prot defines it, and smc_destruct() returns early unless sk_state is SMC_CLOSED. As a result, every failing socket(AF_INET, SOCK_STREAM, IPPROTO_SMC) call leaks one tcp_sock, so an unprivileged task able to attach a deny-all BPF_CGROUP_INET_SOCK_CREATE program to its own cgroup can grow kernel memory unboundedly. Add a .destroy hook to both protos that releases the clcsock via smc_clcsock_release(). smc_sk_init() hashes the sock into the smc hashinfo before the clcsock is created, and smc_diag dumps walk that hash dereferencing smc->clcsock without taking clcsock_release_lock, while sk_common_release() calls .destroy before .unhash. Unhash the sock before releasing the clcsock, as __smc_release() does, so a concurrent dump cannot observe the release; the second unhash in sk_common_release() is a no-op. Fixes: d25a92ccae6b ("net/smc: Introduce IPPROTO_SMC") Reported-by: Abaci Assisted-by: abaci:qwen3.8-max Signed-off-by: Yifei Chu Reviewed-by: Dust Li Link: https://patch.msgid.link/178753843966.342810.566471390946765094@linux.alibaba.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net/smc: free pending qentry in smc_llc_flow_stop() before memset

2026-09-14T11:41:02+00:00

[ Upstream commit 5ee0ceddc7785c6dcf4a8107fef01f0414a354f4 ] smc_llc_flow_stop() resets a flow struct with a blind memset: spin_lock_bh(&lgr->llc_flow_lock); memset(flow, 0, sizeof(*flow)); flow->type = SMC_LLC_FLOW_NONE; spin_unlock_bh(&lgr->llc_flow_lock); If flow->qentry is non-NULL at this point the pointer is overwritten without the allocation being freed, leaking one kmalloc object. A late-arriving duplicate CONFIRM_LINK or ADD_LINK_CONT message can set flow->qentry after the legitimate message has been consumed by the waiter via smc_llc_flow_qentry_clr() (which NULLs the pointer but leaves flow->type non-zero) but before the flow completes and smc_llc_flow_stop() runs. In that window the duplicate is stashed into flow->qentry, and then lost when smc_llc_flow_stop() zeros the struct. Call smc_llc_flow_qentry_del() inside the lock before the memset. smc_llc_flow_qentry_del() already checks flow->qentry before freeing, so the normal case where no entry is pending is a no-op. Fixes: 555da9af827d ("net/smc: add event-based llc_flow framework") Reviewed-by: Hidayath Khan Signed-off-by: Mahanta Jambigi Link: https://patch.msgid.link/20260818073943.1108383-1-mjambigi@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/smc: free stashed qentry before overwrite in REQ_ADD_LINK to ADD_LINK transition

2026-09-14T11:41:01+00:00

[ Upstream commit 036322025d6e440cb75fc6fecbba9a16b271a2ae ] When smc_llc_event_handler() transitions the local LLC flow from SMC_LLC_FLOW_REQ_ADD_LINK to SMC_LLC_FLOW_ADD_LINK on arrival of an ADD_LINK request, it calls smc_llc_flow_qentry_set() unconditionally: if (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_REQ_ADD_LINK) { lgr->llc_flow_lcl.type = SMC_LLC_FLOW_ADD_LINK; smc_llc_flow_qentry_set(&lgr->llc_flow_lcl, qentry); ... } A CONFIRM_LINK or ADD_LINK_CONT arriving while flow->type is SMC_LLC_FLOW_REQ_ADD_LINK is stashed into flow->qentry via the SMC_LLC_CONFIRM_LINK / SMC_LLC_ADD_LINK_CONT handler (which stores into flow->qentry for any non-NONE flow type). When the subsequent ADD_LINK arrives, the REQ_ADD_LINK branch overwrites flow->qentry with the new pointer without first freeing the stashed allocation, leaking one kmalloc object. The stashed entry has no consumer: smc_llc_wait() is only called from llc_add_link_work, which is not yet scheduled while the flow type remains REQ_ADD_LINK. No waiter is sleeping on llc_msg_waiter at this point. It is safe to unconditionally free any stashed qentry before the overwrite. Call smc_llc_flow_qentry_del() before smc_llc_flow_qentry_set() in the REQ_ADD_LINK branch. smc_llc_flow_qentry_del() already checks flow->qentry before freeing, so the normal path where no entry is stashed is a no-op. Fixes: b4ba4652b3f8 ("net/smc: extend LLC layer for SMC-Rv2") Reviewed-by: Hidayath Khan Signed-off-by: Mahanta Jambigi Link: https://patch.msgid.link/20260818073107.466506-1-mjambigi@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/smc: hash socket only after full initialisation in smc_sk_init()

2026-09-14T11:40:55+00:00

[ Upstream commit 8acf691d8017012e1476c30e7381513c1e929c94 ] smc_sk_init() calls sk->sk_prot->hash(sk) before several fields are fully initialised: clcsock_release_lock, the saved clcsk_* callbacks, use_fallback/fallback_rsn, and conn.close_work. Once hash() returns the socket is visible to concurrent hash walkers, which can then observe uninitialised state. Move hash(sk) to the end of smc_sk_init() so the socket is published only after it is fully constructed. Fixes: d0e35656d834 ("net/smc: refactoring initialization of smc sock") Reviewed-by: Hidayath Khan Reviewed-by: Sidraya Jayagond Signed-off-by: Mahanta Jambigi Link: https://patch.msgid.link/20260813074315.554926-1-mjambigi@linux.ibm.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net/smc: unregister the connection before draining the rx tasklet

2026-09-07T15:37:21+00:00

commit 36cdf5d48ca191dcd71c28cadbe0981b1d25318d upstream. smc_conn_free() calls smc_ism_unset_conn() only while the link group is still on its device list, and never sets conn->killed. smc_lgr_terminate_sched() unlinks the group immediately and defers killing its connections to a work item, so a connection freed in that window keeps its smcd->conn[] slot with both gates in smcd_handle_irq() open, and the device can re-arm the receive tasklet after tasklet_kill() has returned. On the DMB-nocopy path the ghost send buffer is freed right after that drain, so the re-armed tasklet dereferences it. Unregister unconditionally and drain before the detach at both teardown sites, mirroring rmb_desc, which smc_buf_unuse() releases after the drain. Clear conn->sndbuf_desc before freeing it as well, so a reader that samples the pointer cannot get one that is already freed. Fixes: ae2be35cbed2 ("net/smc: {at|de}tach sndbuf to peer DMB if supported") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Reviewed-by: Sidraya Jayagond Reviewed-by: Tony Lu Link: https://patch.msgid.link/20260808-b4-disp-22f119e6-v2-1-61647601a6f3@proton.me Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/smc: stop killed, freed and out_of_sync sharing a byte

2026-09-07T15:37:21+00:00

commit db51a8658c11a82432b64999519a269c3aabb447 upstream. The three connection state flags are single-bit bitfields, so they occupy one byte of struct smc_connection and every store to one is a read-modify-write of the other two: u8 killed : 1; u8 freed : 1; u8 out_of_sync : 1; They are not written under a common lock. smc_cdc_msg_validate() sets out_of_sync from the receive tasklet, while smc_conn_kill() sets killed from process context under lock_sock(), and the receive path does not defer to the backlog when the socket is owned -- smc_cdc_msg_recv() takes only bh_lock_sock(). Give each flag its own byte so a store no longer touches its neighbours. All readers test them as booleans and are unchanged. struct smc_connection grows by two bytes. Fixes: b286a0651e44 ("net/smc: handle incoming CDC validation message") Cc: stable@vger.kernel.org Reviewed-by: Mahanta Jambigi Signed-off-by: Hidayath Khan Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260820074642.966856-2-hidayath@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link()

2026-09-07T15:37:20+00:00

commit a42a459ef0e54cb0c4b3e43e21cb0e658e664f64 upstream. smc_llc_srv_add_link() keeps add_llc pointing into the queue entry: add_llc = &qentry->msg.add_link; smc_llc.c:1482 ... smc_llc_save_add_link_info(link_new, add_llc); smc_llc.c:1494 smc_llc_flow_qentry_del(&lgr->llc_flow_lcl); smc_llc.c:1495 ... u8 *llc_msg = smc_link_shared_v2_rxbuf(link) ? (u8 *)lgr->wr_rx_buf_v2 : (u8 *)add_llc; smc_llc.c:1504 smc_llc_save_add_link_rkeys(link, link_new, llc_msg); smc_llc.c:1506 smc_llc_flow_qentry_del() kfree()s the entry, so on a link without a shared v2 receive buffer the pointer handed to smc_llc_save_add_link_rkeys() is already freed. Before the Fixes: commit that branch always used lgr->wr_rx_buf_v2 and add_llc was not used after the free. Reproduced on an unpatched tree over rxe, with KASAN, kasan_multi_shot and a link forced to max_recv_sge == 1: the entry is freed and read by the same call, and the freeing frame is smc_llc_srv_add_link() itself. [ 2.523161] BUG: KASAN: slab-use-after-free in smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523499] Read of size 2 at addr ffff8880052194de by task kworker/0:1/11 [ 2.523789] [ 2.523862] CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 7.2.0-rc5-p0-g2c9dd296545d #35 PREEMPT(lazy) [ 2.523865] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 2.523866] Workqueue: smc_hs_wq smc_listen_work [ 2.523869] Call Trace: [ 2.523870] [ 2.523871] dump_stack_lvl+0x53/0x70 [ 2.523872] print_report+0xd0/0x630 [ 2.523874] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 [ 2.523876] ? smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523878] kasan_report+0xce/0x100 [ 2.523879] ? smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523881] smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523883] ? smcr_buf_reg_lgr+0x2a4/0x660 [ 2.523885] smc_llc_srv_add_link+0xaa2/0x1e50 [ 2.523888] ? _printk+0xba/0xf0 [ 2.523897] ? __pfx_smc_llc_srv_add_link+0x10/0x10 [ 2.523899] ? down_write+0xb0/0x130 [ 2.523903] ? __pfx_down_write+0x10/0x10 [ 2.523905] smc_listen_work+0x489e/0x4d00 [ 2.523907] ? kmem_cache_free+0x1c6/0x3a0 [ 2.523911] ? __pfx_smc_listen_work+0x10/0x10 [ 2.523913] ? release_sock+0x148/0x1d0 [ 2.523915] ? smc_tcp_listen_work+0xb4f/0xfc0 [ 2.523917] ? _raw_spin_lock_irq+0x80/0xe0 [ 2.523918] ? __pfx__raw_spin_lock_irq+0x10/0x10 [ 2.523920] process_one_work+0x633/0x1030 [ 2.523922] ? assign_work+0x11d/0x370 [ 2.523924] worker_thread+0x45b/0xd10 [ 2.523926] ? __pfx_worker_thread+0x10/0x10 [ 2.523928] ? __pfx_worker_thread+0x10/0x10 [ 2.523929] kthread+0x2c6/0x3b0 [ 2.523931] ? recalc_sigpending+0x15c/0x1e0 [ 2.523934] ? __pfx_kthread+0x10/0x10 [ 2.523935] ret_from_fork+0x36e/0x5a0 [ 2.523937] ? __pfx_ret_from_fork+0x10/0x10 [ 2.523938] ? __switch_to+0x572/0xdd0 [ 2.523943] ? __pfx_kthread+0x10/0x10 [ 2.523944] ret_from_fork_asm+0x1a/0x30 [ 2.523947] [ 2.523948] [ 2.531253] Allocated by task 48: [ 2.531399] kasan_save_stack+0x33/0x60 [ 2.531570] kasan_save_track+0x14/0x30 [ 2.531737] __kasan_kmalloc+0x8f/0xa0 [ 2.531905] __kmalloc_cache_noprof+0x158/0x370 [ 2.532100] smc_llc_enqueue+0x72/0x560 [ 2.532268] smc_wr_rx_tasklet_fn+0x474/0xa80 [ 2.532491] tasklet_action_common+0x20f/0x8a0 [ 2.532714] handle_softirqs+0x18e/0x590 [ 2.532886] do_softirq+0x3b/0x60 [ 2.533036] __local_bh_enable_ip+0x61/0x70 [ 2.533221] __alloc_skb+0x732/0x890 [ 2.533384] rxe_init_packet+0x16b/0x4f0 [ 2.533567] prepare_ack_packet+0xb8/0x830 [ 2.533760] rxe_receiver+0x495/0x96e0 [ 2.533933] do_work+0x144/0x470 [ 2.534078] process_one_work+0x633/0x1030 [ 2.534257] worker_thread+0x45b/0xd10 [ 2.534424] kthread+0x2c6/0x3b0 [ 2.534569] ret_from_fork+0x36e/0x5a0 [ 2.534737] ret_from_fork_asm+0x1a/0x30 [ 2.534907] [ 2.534980] Freed by task 11: [ 2.535112] kasan_save_stack+0x33/0x60 [ 2.535279] kasan_save_track+0x14/0x30 [ 2.535444] kasan_save_free_info+0x3b/0x60 [ 2.535625] __kasan_slab_free+0x43/0x70 [ 2.535798] kfree+0x121/0x380 [ 2.535935] smc_llc_srv_add_link+0x9a8/0x1e50 [ 2.536128] smc_listen_work+0x489e/0x4d00 [ 2.536305] process_one_work+0x633/0x1030 [ 2.536482] worker_thread+0x45b/0xd10 [ 2.536652] kthread+0x2c6/0x3b0 [ 2.536794] ret_from_fork+0x36e/0x5a0 [ 2.536958] ret_from_fork_asm+0x1a/0x30 [ 2.537133] [ 2.537205] The buggy address belongs to the object at ffff888005219480 [ 2.537205] which belongs to the cache kmalloc-96 of size 96 [ 2.537719] The buggy address is located 94 bytes inside of [ 2.537719] freed 96-byte region [ffff888005219480, ffff8880052194e0) [ 2.538216] [ 2.538289] The buggy address belongs to the physical page: [ 2.538524] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5219 [ 2.538857] flags: 0x100000000000000(node=0|zone=1) [ 2.539066] page_type: f5(slab) [ 2.539210] raw: 0100000000000000 ffff888001041280 dead000000000122 0000000000000000 [ 2.539534] raw: 0000000000000000 0000000000200020 00000000f5000000 0000000000000000 [ 2.539863] page dumped because: kasan: bad access detected [ 2.540098] [ 2.540170] Memory state around the buggy address: [ 2.540379] ffff888005219380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 2.540684] ffff888005219400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 2.540988] >ffff888005219480: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc [ 2.541291] ^ [ 2.541548] ffff888005219500: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc [ 2.541857] ffff888005219580: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc The offset is past the 72-byte queue entry because the out-of-bounds read fixed by the next patch is on the same line; what this patch removes is the free at smc_llc_srv_add_link+0x9a8 happening before the read at +0xaa2. Detach the entry instead of freeing it there, and free it at the single exit label. The reject path has to detach as well, otherwise it would be freed twice. This changes only the lifetime of the entry. The same read still runs past its end until the next two patches bound it, so a backport wants all three. Fixes: 27ef6a9981fe ("net/smc: support SMC-R V2 for rdma devices with max_recv_sge equals to 1") Cc: stable@vger.kernel.org Reviewed-by: Sidraya Jayagond Signed-off-by: Yehyeong Lee Reviewed-by: Breno Leitao Link: https://patch.msgid.link/20260819023306.644849-2-yhlee@isslab.korea.ac.kr Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/smc: fix use-after-free in smc_rx_pipe_buf_release()

2026-09-07T15:37:20+00:00

commit c924884743e948e25625b7fbf3ee2a9325a204a7 upstream. smc_rx_splice() hands RMB pages to a pipe and takes a socket reference per entry so the smc_sock stays alive until the reader finishes. The connection does not: a concurrent close runs smc_conn_free(), which releases the receive buffer back to the link group pool. smc_rx_pipe_buf_release() tests sk_state before taking the socket lock. The state can change between the test and the lock, and smc_rx_update_cons() then dereferences conn->rmb_desc and walks conn->lgr, which smc_conn_free() has already released. On the is_reg_err path smcr_buf_unuse() frees the descriptor outright, so this is a use-after-free. Take the socket lock first and test conn->freed instead. smc_conn_free() sets that flag before releasing anything, and every caller holds the socket lock. The two paths exclude each other: either the pipe release runs first with everything valid, or it sees the flag and skips the update. Fixes: 9014db202cb7 ("smc: add support for splice()") Cc: stable@vger.kernel.org Reviewed-by: Mahanta Jambigi Signed-off-by: Hidayath Khan Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260820074642.966856-3-hidayath@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/smc: fix socket refcount leak in smc_switch_conns()

2026-09-07T15:37:20+00:00

commit 719296c4aa8213d4ac8002e77d5956d436bc98d0 upstream. smc_switch_conns() takes a reference on the SMC socket before dropping lgr->conns_lock, so the connection stays alive while the CDC slot is fetched: sock_hold(&smc->sk); read_unlock_bh(&lgr->conns_lock); /* pre-fetch buffer outside of send_lock, might sleep */ rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend); if (rc) goto err_out; The err_out label only drops the wr_tx link reference, so this early exit returns without the matching sock_put(). The second error exit is not affected, because sock_put() has already run by then. A leaked sk_refcnt means the smc_sock is never destroyed. Its send and receive buffers stay allocated, and for a user socket the reference held on the network namespace is never released, so the netns can no longer be torn down. smc_cdc_get_free_slot() fails when the target link goes down or when the connection has been killed while the switch is in progress. Both are reachable during the link failover this function implements, so the leak is triggered by the same hardware events that make smc_switch_conns() run in the first place. Restructure so there is a single sock_put() covering both outcomes, instead of adding a second one to the error path. Fixes: 95f7f3e7dc6b ("net/smc: improved fix wait on already cleared link") Cc: stable@vger.kernel.org Reviewed-by: Mahanta Jambigi Reviewed-by: Breno Leitao Signed-off-by: Hidayath Khan Link: https://patch.msgid.link/20260820144729.1019399-1-hidayath@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/smc: do not dereference an unset send buffer on the SMC-D teardown path

2026-09-07T15:37:20+00:00

commit b395dd319cea422239cb45b998fb38d7e373af87 upstream. smc_close_stream_wait() calls smc_tx_prepared_sends() from inside its sk_wait_event() condition, and sk_wait_event() evaluates that condition once with the socket lock released. smcd_buf_detach() clears conn->sndbuf_desc from smc_conn_kill() under lock_sock(), so a link group terminating while a socket waits there leaves the helper dereferencing NULL, faulting out of close(). SIOCOUTQ reads the field by hand, and smc_close_cancel_work() drops the lock across two cancel_*_sync() calls. Sample the pointer once in the helper, report nothing prepared while it is unset, and bound the ioctl the same way. The receive tasklet dereferences the field directly in smc_cdc_msg_recv_action(), not through this helper; 1/2 is what keeps it from running that late. Fixes: ae2be35cbed2 ("net/smc: {at|de}tach sndbuf to peer DMB if supported") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Reviewed-by: Sidraya Jayagond Reviewed-by: Tony Lu Link: https://patch.msgid.link/20260808-b4-disp-22f119e6-v2-2-61647601a6f3@proton.me Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman