From: Kuniyuki Iwashima <kuniyu@google.com> mainline inclusion from mainline-v7.1-rc1 commit 965dc93481d1b80d341bdd16c27b16fe197175ee category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/15707 CVE: CVE-2026-53005 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- SOCKMAP can hide inflight fd from AF_UNIX GC. When a socket in SOCKMAP receives skb with inflight fd, sk_psock_verdict_data_ready() looks up the mapped socket and enqueue skb to its psock->ingress_skb. Since neither the old nor the new GC can inspect the psock queue, the hidden skb leaks the inflight sockets. Note that this cannot be detected via kmemleak because inflight sockets are linked to a global list. In addition, SOCKMAP redirect breaks the Tarjan-based GC's assumption that unix_edge.successor is always alive, which is no longer true once skb is redirected, resulting in use-after-free below. [0] Moreover, SOCKMAP does not call scm_stat_del() properly, so unix_show_fdinfo() could report an incorrect fd count. sk_msg_recvmsg() does not support any SCM attributes in the first place. Let's drop all SCM attributes before passing skb to the SOCKMAP layer. [0]: BUG: KASAN: slab-use-after-free in unix_del_edges (net/unix/garbage.c:118 net/unix/garbage.c:181 net/unix/garbage.c:251) Read of size 8 at addr ffff888125362670 by task kworker/56:1/496 CPU: 56 UID: 0 PID: 496 Comm: kworker/56:1 Not tainted 7.0.0-rc7-00263-gb9d8b856689d #3 PREEMPT(lazy) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 Workqueue: events sk_psock_backlog Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:122) print_report (mm/kasan/report.c:379) kasan_report (mm/kasan/report.c:597) unix_del_edges (net/unix/garbage.c:118 net/unix/garbage.c:181 net/unix/garbage.c:251) unix_destroy_fpl (net/unix/garbage.c:317) unix_destruct_scm (./include/net/scm.h:80 ./include/net/scm.h:86 net/unix/af_unix.c:1976) sk_psock_backlog (./include/linux/skbuff.h:?) process_scheduled_works (kernel/workqueue.c:?) worker_thread (kernel/workqueue.c:?) kthread (kernel/kthread.c:438) ret_from_fork (arch/x86/kernel/process.c:164) ret_from_fork_asm (arch/x86/entry/entry_64.S:258) </TASK> Allocated by task 955: kasan_save_track (mm/kasan/common.c:58 mm/kasan/common.c:78) __kasan_slab_alloc (mm/kasan/common.c:369) kmem_cache_alloc_noprof (mm/slub.c:4539) sk_prot_alloc (net/core/sock.c:2240) sk_alloc (net/core/sock.c:2301) unix_create1 (net/unix/af_unix.c:1099) unix_create (net/unix/af_unix.c:1169) __sock_create (net/socket.c:1606) __sys_socketpair (net/socket.c:1811) __x64_sys_socketpair (net/socket.c:1863 net/socket.c:1860 net/socket.c:1860) do_syscall_64 (arch/x86/entry/syscall_64.c:?) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) Freed by task 496: kasan_save_track (mm/kasan/common.c:58 mm/kasan/common.c:78) kasan_save_free_info (mm/kasan/generic.c:587) __kasan_slab_free (mm/kasan/common.c:287) kmem_cache_free (mm/slub.c:6165) __sk_destruct (net/core/sock.c:2282 net/core/sock.c:2384) sk_psock_destroy (./include/net/sock.h:?) process_scheduled_works (kernel/workqueue.c:?) worker_thread (kernel/workqueue.c:?) kthread (kernel/kthread.c:438) ret_from_fork (arch/x86/kernel/process.c:164) ret_from_fork_asm (arch/x86/entry/entry_64.S:258) Fixes: c63829182c37 ("af_unix: Implement ->psock_update_sk_prot()") Fixes: 77462de14a43 ("af_unix: Add read_sock for stream socket types") Reported-by: Xingyu Jin <xingyuj@google.com> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com> Link: https://patch.msgid.link/20260415184830.3988432-1-kuniyu@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Conflicts: net/unix/af_unix.c [commit d0aac85449de ("af_unix: Don't use skb_recv_datagram() in unix_stream_read_skb().") and commit 2b9996417e4e ("af_unix/scm: fix whitespace errors") are not backported, which lead to conflicts] Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/unix/af_unix.c | 32 ++++++++++++++++++++++++-------- 1 file changed, 24 insertions(+), 8 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index d20b43a13ffc..da0e477b96a7 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1854,16 +1854,18 @@ static void unix_peek_fds(struct scm_cookie *scm, struct sk_buff *skb) static void unix_destruct_scm(struct sk_buff *skb) { - struct scm_cookie scm; + struct scm_cookie scm = {}; - memset(&scm, 0, sizeof(scm)); - scm.pid = UNIXCB(skb).pid; + swap(scm.pid, UNIXCB(skb).pid); if (UNIXCB(skb).fp) unix_detach_fds(&scm, skb); - /* Alas, it calls VFS */ - /* So fscking what? fput() had been SMP-safe since the last Summer */ scm_destroy(&scm); +} + +static void unix_wfree(struct sk_buff *skb) +{ + unix_destruct_scm(skb); sock_wfree(skb); } @@ -1879,7 +1881,7 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen if (scm->fp && send_fds) err = unix_attach_fds(scm, skb); - skb->destructor = unix_destruct_scm; + skb->destructor = unix_wfree; return err; } @@ -1940,6 +1942,13 @@ static void scm_stat_del(struct sock *sk, struct sk_buff *skb) } } +static void unix_orphan_scm(struct sock *sk, struct sk_buff *skb) +{ + scm_stat_del(sk, skb); + unix_destruct_scm(skb); + skb->destructor = sock_wfree; +} + /* * Send AF_UNIX data. */ @@ -2517,9 +2526,14 @@ static int unix_read_skb(struct sock *sk, skb_read_actor_t recv_actor) mutex_lock(&u->iolock); skb = skb_recv_datagram(sk, MSG_DONTWAIT, &err); - mutex_unlock(&u->iolock); - if (!skb) + if (!skb) { + mutex_unlock(&u->iolock); return err; + } + + unix_orphan_scm(sk, skb); + + mutex_unlock(&u->iolock); return recv_actor(sk, skb); } @@ -2708,6 +2722,8 @@ static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor) } #endif + unix_orphan_scm(sk, skb); + return recv_actor(sk, skb); } -- 2.43.0