kernel/linux.git/net/atm, branch v6.19.12

atm: lec: fix use-after-free in sock_def_readable()

2026-04-11T12:29:20+00:00

[ Upstream commit 922814879542c2e397b0e9641fd36b8202a8e555 ] A race condition exists between lec_atm_close() setting priv->lecd to NULL and concurrent access to priv->lecd in send_to_lecd(), lec_handle_bridge(), and lec_atm_send(). When the socket is freed via RCU while another thread is still using it, a use-after-free occurs in sock_def_readable() when accessing the socket's wait queue. The root cause is that lec_atm_close() clears priv->lecd without any synchronization, while callers dereference priv->lecd without any protection against concurrent teardown. Fix this by converting priv->lecd to an RCU-protected pointer: - Mark priv->lecd as __rcu in lec.h - Use rcu_assign_pointer() in lec_atm_close() and lecd_attach() for safe pointer assignment - Use rcu_access_pointer() for NULL checks that do not dereference the pointer in lec_start_xmit(), lec_push(), send_to_lecd() and lecd_attach() - Use rcu_read_lock/rcu_dereference/rcu_read_unlock in send_to_lecd(), lec_handle_bridge() and lec_atm_send() to safely access lecd - Use rcu_assign_pointer() followed by synchronize_rcu() in lec_atm_close() to ensure all readers have completed before proceeding. This is safe since lec_atm_close() is called from vcc_release() which holds lock_sock(), a sleeping lock. - Remove the manual sk_receive_queue drain from lec_atm_close() since vcc_destroy_socket() already drains it after lec_atm_close() returns. v2: Switch from spinlock + sock_hold/put approach to RCU to properly fix the race. The v1 spinlock approach had two issues pointed out by Eric Dumazet: 1. priv->lecd was still accessed directly after releasing the lock instead of using a local copy. 2. The spinlock did not prevent packets being queued after lec_atm_close() drains sk_receive_queue since timer and workqueue paths bypass netif_stop_queue(). Note: Syzbot patch testing was attempted but the test VM terminated unexpectedly with "Connection to localhost closed by remote host", likely due to a QEMU AHCI emulation issue unrelated to this fix. Compile testing with "make W=1 net/atm/lec.o" passes cleanly. Reported-by: syzbot+f50072212ab792c86925@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f50072212ab792c86925 Link: https://lore.kernel.org/all/20260309093614.502094-1-kartikey406@gmail.com/T/ [v1] Signed-off-by: Deepanshu Kartikey Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260309155908.508768-1-kartikey406@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

atm: lec: fix null-ptr-deref in lec_arp_clear_vccs

2026-03-12T11:09:46+00:00

[ Upstream commit 101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb ] syzkaller reported a null-ptr-deref in lec_arp_clear_vccs(). This issue can be easily reproduced using the syzkaller reproducer. In the ATM LANE (LAN Emulation) module, the same atm_vcc can be shared by multiple lec_arp_table entries (e.g., via entry->vcc or entry->recv_vcc). When the underlying VCC is closed, lec_vcc_close() iterates over all ARP entries and calls lec_arp_clear_vccs() for each matched entry. For example, when lec_vcc_close() iterates through the hlists in priv->lec_arp_empty_ones or other ARP tables: 1. In the first iteration, for the first matched ARP entry sharing the VCC, lec_arp_clear_vccs() frees the associated vpriv (which is vcc->user_back) and sets vcc->user_back to NULL. 2. In the second iteration, for the next matched ARP entry sharing the same VCC, lec_arp_clear_vccs() is called again. It obtains a NULL vpriv from vcc->user_back (via LEC_VCC_PRIV(vcc)) and then attempts to dereference it via `vcc->pop = vpriv->old_pop`, leading to a null-ptr-deref crash. Fix this by adding a null check for vpriv before dereferencing it. If vpriv is already NULL, it means the VCC has been cleared by a previous call, so we can safely skip the cleanup and just clear the entry's vcc/recv_vcc pointers. The entire cleanup block (including vcc_release_async()) is placed inside the vpriv guard because a NULL vpriv indicates the VCC has already been fully released by a prior iteration — repeating the teardown would redundantly set flags and trigger callbacks on an already-closing socket. The Fixes tag points to the initial commit because the entry->vcc path has been vulnerable since the original code. The entry->recv_vcc path was later added by commit 8d9f73c0ad2f ("atm: fix a memory leak of vcc->user_back") with the same pattern, and both paths are fixed here. Reported-by: syzbot+72e3ea390c305de0e259@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68c95a83.050a0220.3c6139.0e5c.GAE@google.com/T/ Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Suggested-by: Dan Carpenter Reviewed-by: Simon Horman Signed-off-by: Jiayuan Chen Link: https://patch.msgid.link/20260225123250.189289-1-jiayuan.chen@linux.dev Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: atm: fix crash due to unvalidated vcc pointer in sigd_send()

2026-02-26T23:01:13+00:00

[ Upstream commit ae88a5d2f29b69819dc7b04086734439d074a643 ] Reproducer available at [1]. The ATM send path (sendmsg -> vcc_sendmsg -> sigd_send) reads the vcc pointer from msg->vcc and uses it directly without any validation. This pointer comes from userspace via sendmsg() and can be arbitrarily forged: int fd = socket(AF_ATMSVC, SOCK_DGRAM, 0); ioctl(fd, ATMSIGD_CTRL); // become ATM signaling daemon struct msghdr msg = { .msg_iov = &iov, ... }; *(unsigned long *)(buf + 4) = 0xdeadbeef; // fake vcc pointer sendmsg(fd, &msg, 0); // kernel dereferences 0xdeadbeef In normal operation, the kernel sends the vcc pointer to the signaling daemon via sigd_enq() when processing operations like connect(), bind(), or listen(). The daemon is expected to return the same pointer when responding. However, a malicious daemon can send arbitrary pointer values. Fix this by introducing find_get_vcc() which validates the pointer by searching through vcc_hash (similar to how sigd_close() iterates over all VCCs), and acquires a reference via sock_hold() if found. Since struct atm_vcc embeds struct sock as its first member, they share the same lifetime. Therefore using sock_hold/sock_put is sufficient to keep the vcc alive while it is being used. Note that there may be a race with sigd_close() which could mark the vcc with various flags (e.g., ATM_VF_RELEASED) after find_get_vcc() returns. However, sock_hold() guarantees the memory remains valid, so this race only affects the logical state, not memory safety. [1]: https://gist.github.com/mrpre/1ba5949c45529c511152e2f4c755b0f3 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+1f22cb1769f249df9fa0@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/69039850.a70a0220.5b2ed.005d.GAE@google.com/T/ Signed-off-by: Jiayuan Chen Link: https://patch.msgid.link/20260205095501.131890-1-jiayuan.chen@linux.dev Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

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

2025-11-27T20:19:08+00:00

Conflicts: net/xdp/xsk.c 0ebc27a4c67d ("xsk: avoid data corruption on cq descriptor number") 8da7bea7db69 ("xsk: add indirect call for xsk_destruct_skb") 30ed05adca4a ("xsk: use a smaller new lock for shared pool case") https://lore.kernel.org/20251127105450.4a1665ec@canb.auug.org.au https://lore.kernel.org/eb4eee14-7e24-4d1b-b312-e9ea738fefee@kernel.org Signed-off-by: Jakub Kicinski

net: atm: fix incorrect cleanup function call in error path

2025-11-21T02:09:49+00:00

In atm_init(), if atmsvc_init() fails, the code jumps to out_atmpvc_exit label which incorrectly calls atmsvc_exit() instead of atmpvc_exit(). This results in calling the wrong cleanup function and failing to properly clean up atmpvc_init(). Fix this by calling atmpvc_exit() in the out_atmpvc_exit error path. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Sayooj K Karun Link: https://patch.msgid.link/20251119085747.67139-1-sayooj@aerlync.com Signed-off-by: Jakub Kicinski

net: Convert proto_ops connect() callbacks to use sockaddr_unsized

2025-11-05T03:10:32+00:00

Update all struct proto_ops connect() callback function prototypes from "struct sockaddr *" to "struct sockaddr_unsized *" to avoid lying to the compiler about object sizes. Calls into struct proto handlers gain casts that will be removed in the struct proto conversion patch. No binary changes expected. Signed-off-by: Kees Cook Link: https://patch.msgid.link/20251104002617.2752303-3-kees@kernel.org Signed-off-by: Jakub Kicinski

net: Convert proto_ops bind() callbacks to use sockaddr_unsized

2025-11-05T03:10:32+00:00

Update all struct proto_ops bind() callback function prototypes from "struct sockaddr *" to "struct sockaddr_unsized *" to avoid lying to the compiler about object sizes. Calls into struct proto handlers gain casts that will be removed in the struct proto conversion patch. No binary changes expected. Signed-off-by: Kees Cook Link: https://patch.msgid.link/20251104002617.2752303-2-kees@kernel.org Signed-off-by: Jakub Kicinski

neighbour: Convert rwlock of struct neigh_table to spinlock.

2025-10-25T00:57:20+00:00

Only neigh_for_each() and neigh_seq_start/stop() are on the reader side of neigh_table.lock. Let's convert rwlock to the plain spinlock. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20251022054004.2514876-6-kuniyu@google.com Signed-off-by: Jakub Kicinski

net: add SK_WMEM_ALLOC_BIAS constant

2025-10-15T16:04:21+00:00

sk->sk_wmem_alloc is initialized to 1, and sk_wmem_alloc_get() takes care of this initial value. Add SK_WMEM_ALLOC_BIAS define to not spread this magic value. Signed-off-by: Eric Dumazet Reviewed-by: Neal Cardwell Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20251013152234.842065-2-edumazet@google.com Signed-off-by: Jakub Kicinski

net: atm: fix memory leak in atm_register_sysfs when device_register fail

2025-09-04T07:53:44+00:00

When device_register() return error in atm_register_sysfs(), which can be triggered by kzalloc fail in device_private_init() or other reasons, kmemleak reports the following memory leaks: unreferenced object 0xffff88810182fb80 (size 8): comm "insmod", pid 504, jiffies 4294852464 hex dump (first 8 bytes): 61 64 75 6d 6d 79 30 00 adummy0. backtrace (crc 14dfadaf): __kmalloc_node_track_caller_noprof+0x335/0x450 kvasprintf+0xb3/0x130 kobject_set_name_vargs+0x45/0x120 dev_set_name+0xa9/0xe0 atm_register_sysfs+0xf3/0x220 atm_dev_register+0x40b/0x780 0xffffffffa000b089 do_one_initcall+0x89/0x300 do_init_module+0x27b/0x7d0 load_module+0x54cd/0x5ff0 init_module_from_file+0xe4/0x150 idempotent_init_module+0x32c/0x610 __x64_sys_finit_module+0xbd/0x120 do_syscall_64+0xa8/0x270 entry_SYSCALL_64_after_hwframe+0x77/0x7f When device_create_file() return error in atm_register_sysfs(), the same issue also can be triggered. Function put_device() should be called to release kobj->name memory and other device resource, instead of kfree(). Fixes: 1fa5ae857bb1 ("driver core: get rid of struct device's bus_id string array") Signed-off-by: Wang Liang Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250901063537.1472221-1-wangliang74@huawei.com Signed-off-by: Paolo Abeni