kernel/linux.git/net/smc, branch v6.6.156

smc: Use __sk_dst_get() and dst_dev_rcu() in smc_vlan_by_tcpsk().

2026-09-02T12:29:17+00:00

[ Upstream commit 0b0e4d51c6554e5ecc3f8cc73c2eaf12da21249a ] smc_vlan_by_tcpsk() fetches sk_dst_get(sk)->dev before RTNL and passes it to netdev_walk_all_lower_dev(), which is illegal. Also, smc_vlan_by_tcpsk_walk() does not require RTNL at all. Let's use __sk_dst_get(), dst_dev_rcu(), and netdev_walk_all_lower_dev_rcu(). Note that the returned value of smc_vlan_by_tcpsk() is not used in the caller. Fixes: 0cfdd8f92cac ("smc: connection and link group creation") Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250916214758.650211-5-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

smc: Use __sk_dst_get() and dst_dev_rcu() in smc_clc_prfx_match().

2026-09-02T12:29:17+00:00

[ Upstream commit 235f81045c008169cc4e1955b4a64e118eebe61b ] smc_clc_prfx_match() is called from smc_listen_work() and not under RCU nor RTNL. Using sk_dst_get(sk)->dev could trigger UAF. Let's use __sk_dst_get() and dst_dev_rcu(). Note that the returned value of smc_clc_prfx_match() is not used in the caller. Fixes: a046d57da19f ("smc: CLC handshake (incl. preparation steps)") Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250916214758.650211-4-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().

2026-09-02T12:29:17+00:00

[ Upstream commit 935d783e5de9b64587f3adb25641dd8385e64ddb ] smc_clc_prfx_set() is called during connect() and not under RCU nor RTNL. Using sk_dst_get(sk)->dev could trigger UAF. Let's use __sk_dst_get() and dev_dst_rcu() under rcu_read_lock() after kernel_getsockname(). Note that the returned value of smc_clc_prfx_set() is not used in the caller. While at it, we change the 1st arg of smc_clc_prfx_set[46]_rcu() not to touch dst there. Fixes: a046d57da19f ("smc: CLC handshake (incl. preparation steps)") Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250916214758.650211-3-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

smc: Fix use-after-free in __pnet_find_base_ndev().

2026-09-02T12:29:17+00:00

[ Upstream commit 3d3466878afd8d43ec0ca2facfbc7f03e40d0f79 ] syzbot reported use-after-free of net_device in __pnet_find_base_ndev(), which was called during connect(). [0] smc_pnet_find_ism_resource() fetches sk_dst_get(sk)->dev and passes down to pnet_find_base_ndev(), where RTNL is held. Then, UAF happened at __pnet_find_base_ndev() when the dev is first used. This means dev had already been freed before acquiring RTNL in pnet_find_base_ndev(). While dev is going away, dst->dev could be swapped with blackhole_netdev, and the dev's refcnt by dst will be released. We must hold dev's refcnt before calling smc_pnet_find_ism_resource(). Also, smc_pnet_find_roce_resource() has the same problem. Let's use __sk_dst_get() and dst_dev_rcu() in the two functions. [0]: BUG: KASAN: use-after-free in __pnet_find_base_ndev+0x1b1/0x1c0 net/smc/smc_pnet.c:926 Read of size 1 at addr ffff888036bac33a by task syz.0.3632/18609 CPU: 1 UID: 0 PID: 18609 Comm: syz.0.3632 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 __pnet_find_base_ndev+0x1b1/0x1c0 net/smc/smc_pnet.c:926 pnet_find_base_ndev net/smc/smc_pnet.c:946 [inline] smc_pnet_find_ism_by_pnetid net/smc/smc_pnet.c:1103 [inline] smc_pnet_find_ism_resource+0xef/0x390 net/smc/smc_pnet.c:1154 smc_find_ism_device net/smc/af_smc.c:1030 [inline] smc_find_proposal_devices net/smc/af_smc.c:1115 [inline] __smc_connect+0x372/0x1890 net/smc/af_smc.c:1545 smc_connect+0x877/0xd90 net/smc/af_smc.c:1715 __sys_connect_file net/socket.c:2086 [inline] __sys_connect+0x313/0x440 net/socket.c:2105 __do_sys_connect net/socket.c:2111 [inline] __se_sys_connect net/socket.c:2108 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:2108 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f47cbf8eba9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f47ccdb1038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 00007f47cc1d5fa0 RCX: 00007f47cbf8eba9 RDX: 0000000000000010 RSI: 0000200000000280 RDI: 000000000000000b RBP: 00007f47cc011e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f47cc1d6038 R14: 00007f47cc1d5fa0 R15: 00007ffc512f8aa8 The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888036bacd00 pfn:0x36bac flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000000 ffffea0001243d08 ffff8880b863fdc0 0000000000000000 raw: ffff888036bacd00 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as freed page last allocated via order 2, migratetype Unmovable, gfp_mask 0x446dc0(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_COMP), pid 16741, tgid 16741 (syz-executor), ts 343313197788, free_ts 380670750466 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851 prep_new_page mm/page_alloc.c:1859 [inline] get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416 ___kmalloc_large_node+0x5f/0x1b0 mm/slub.c:4317 __kmalloc_large_node_noprof+0x18/0x90 mm/slub.c:4348 __do_kmalloc_node mm/slub.c:4364 [inline] __kvmalloc_node_noprof+0x6d/0x5f0 mm/slub.c:5067 alloc_netdev_mqs+0xa3/0x11b0 net/core/dev.c:11812 tun_set_iff+0x532/0xef0 drivers/net/tun.c:2775 __tun_chr_ioctl+0x788/0x1df0 drivers/net/tun.c:3085 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 18610 tgid 18608 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1395 [inline] __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895 free_large_kmalloc+0x13a/0x1f0 mm/slub.c:4820 device_release+0x99/0x1c0 drivers/base/core.c:-1 kobject_cleanup lib/kobject.c:689 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x22b/0x480 lib/kobject.c:737 netdev_run_todo+0xd2e/0xea0 net/core/dev.c:11513 rtnl_unlock net/core/rtnetlink.c:157 [inline] rtnl_net_unlock include/linux/rtnetlink.h:135 [inline] rtnl_dellink+0x537/0x710 net/core/rtnetlink.c:3563 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6946 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg+0x219/0x270 net/socket.c:729 ____sys_sendmsg+0x505/0x830 net/socket.c:2614 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668 __sys_sendmsg net/socket.c:2700 [inline] __do_sys_sendmsg net/socket.c:2705 [inline] __se_sys_sendmsg net/socket.c:2703 [inline] __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2703 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff888036bac200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888036bac280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff888036bac300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff888036bac380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888036bac400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff Fixes: 0afff91c6f5e ("net/smc: add pnetid support") Fixes: 1619f770589a ("net/smc: add pnetid support for SMC-D and ISM") Reported-by: syzbot+ea28e9d85be2f327b6c6@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/68c237c7.050a0220.3c6139.0036.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250916214758.650211-2-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: smc: fix splice entry lifetime imbalance in smc_rx_splice

2026-08-19T16:13:12+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 Signed-off-by: Greg Kroah-Hartman

net/smc: fix TOCTOU race between smc_listen_out() and listener close

2026-08-19T16:13:08+00:00

[ Upstream commit 185a4caeecabc150106deda1da170b09f2ad803f ] smc_listen_out() reads lsmc->sk.sk_state without the listener lock, then acquires lock_sock_nested() only after the check passes. This opens a window where smc_close_active() can transition the listener to SMC_CLOSED, call smc_close_cleanup_listen() to drain the accept queue, and release the lock, all between the lockless read and the delayed lock acquisition: smc_listen_work (smc_hs_wq) smc_close_active() ------------------------------- ------------------------- release_sock(child) if (sk_state == SMC_LISTEN) TRUE lock_sock(listener) sk_state = SMC_CLOSED smc_close_cleanup_listen() release_sock(listener) flush_work(tcp_listen_work) lock_sock_nested(listener) smc_accept_enqueue(listener, child) /* child enqueued on dead listener */ smc_close_active() flushes only tcp_listen_work. Work items already dispatched onto smc_hs_wq for the CLC handshake continue running unguarded. smc_accept_enqueue() takes a sock_hold() on the child that is never released, so the child smc_sock, its clcsock, and the reference all leak. A remote peer that opens TCP connections while the server calls close() can exhaust kernel memory. Move lock_sock_nested() to before the sk_state check so that the test and the enqueue are atomic under the listener lock. Fixes: fd57770dd198 ("net/smc: wait for pending work before clcsock release_sock") Reviewed-by: Mahanta Jambigi Signed-off-by: Sidraya Jayagond Reviewed-by: Breno Leitao Reviewed-by: Dust Li Link: https://patch.msgid.link/20260803070701.126339-1-sidraya@linux.ibm.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

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

2026-08-19T16:13:05+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

sysctl: treewide: constify ctl_table_header::ctl_table_arg

2026-08-09T18:22:03+00:00

[ Upstream commit bfa858f220ab8c950dd3e1310fee61950d0ecdae ] To be able to constify instances of struct ctl_tables it is necessary to remove ways through which non-const versions are exposed from the sysctl core. One of these is the ctl_table_arg member of struct ctl_table_header. Constify this reference as a prerequisite for the full constification of struct ctl_table instances. No functional change. Signed-off-by: Thomas Weißschuh Reviewed-by: Kees Cook Signed-off-by: David S. Miller Stable-dep-of: f8d5e7846025 ("sctp: avoid auth_enable sysctl UAF during netns teardown") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

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

2026-08-09T18:21:53+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

2026-07-24T14:03:28+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