kernel/linux.git/net/sctp, branch v6.12.80

sctp: move SCTP_CMD_ASSOC_SHKEY right after SCTP_CMD_PEER_INIT

2026-01-30T09:28:39+00:00

[ Upstream commit a80c9d945aef55b23b54838334345f20251dad83 ] A null-ptr-deref was reported in the SCTP transmit path when SCTP-AUTH key initialization fails: ================================================================== KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f] CPU: 0 PID: 16 Comm: ksoftirqd/0 Tainted: G W 6.6.0 #2 RIP: 0010:sctp_packet_bundle_auth net/sctp/output.c:264 [inline] RIP: 0010:sctp_packet_append_chunk+0xb36/0x1260 net/sctp/output.c:401 Call Trace: sctp_packet_transmit_chunk+0x31/0x250 net/sctp/output.c:189 sctp_outq_flush_data+0xa29/0x26d0 net/sctp/outqueue.c:1111 sctp_outq_flush+0xc80/0x1240 net/sctp/outqueue.c:1217 sctp_cmd_interpreter.isra.0+0x19a5/0x62c0 net/sctp/sm_sideeffect.c:1787 sctp_side_effects net/sctp/sm_sideeffect.c:1198 [inline] sctp_do_sm+0x1a3/0x670 net/sctp/sm_sideeffect.c:1169 sctp_assoc_bh_rcv+0x33e/0x640 net/sctp/associola.c:1052 sctp_inq_push+0x1dd/0x280 net/sctp/inqueue.c:88 sctp_rcv+0x11ae/0x3100 net/sctp/input.c:243 sctp6_rcv+0x3d/0x60 net/sctp/ipv6.c:1127 The issue is triggered when sctp_auth_asoc_init_active_key() fails in sctp_sf_do_5_1C_ack() while processing an INIT_ACK. In this case, the command sequence is currently: - SCTP_CMD_PEER_INIT - SCTP_CMD_TIMER_STOP (T1_INIT) - SCTP_CMD_TIMER_START (T1_COOKIE) - SCTP_CMD_NEW_STATE (COOKIE_ECHOED) - SCTP_CMD_ASSOC_SHKEY - SCTP_CMD_GEN_COOKIE_ECHO If SCTP_CMD_ASSOC_SHKEY fails, asoc->shkey remains NULL, while asoc->peer.auth_capable and asoc->peer.peer_chunks have already been set by SCTP_CMD_PEER_INIT. This allows a DATA chunk with auth = 1 and shkey = NULL to be queued by sctp_datamsg_from_user(). Since command interpretation stops on failure, no COOKIE_ECHO should been sent via SCTP_CMD_GEN_COOKIE_ECHO. However, the T1_COOKIE timer has already been started, and it may enqueue a COOKIE_ECHO into the outqueue later. As a result, the DATA chunk can be transmitted together with the COOKIE_ECHO in sctp_outq_flush_data(), leading to the observed issue. Similar to the other places where it calls sctp_auth_asoc_init_active_key() right after sctp_process_init(), this patch moves the SCTP_CMD_ASSOC_SHKEY immediately after SCTP_CMD_PEER_INIT, before stopping T1_INIT and starting T1_COOKIE. This ensures that if shared key generation fails, authenticated DATA cannot be sent. It also allows the T1_INIT timer to retransmit INIT, giving the client another chance to process INIT_ACK and retry key setup. Fixes: 730fc3d05cd4 ("[SCTP]: Implete SCTP-AUTH parameter processing") Reported-by: Zhen Chen Tested-by: Zhen Chen Signed-off-by: Xin Long Link: https://patch.msgid.link/44881224b375aa8853f5e19b4055a1a56d895813.1768324226.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: Defer SCTP_DBG_OBJCNT_DEC() to sctp_destroy_sock().

2025-12-18T12:54:48+00:00

[ Upstream commit 622e8838a29845316668ec2e7648428878df7f9a ] SCTP_DBG_OBJCNT_INC() is called only when sctp_init_sock() returns 0 after successfully allocating sctp_sk(sk)->ep. OTOH, SCTP_DBG_OBJCNT_DEC() is called in sctp_close(). The code seems to expect that the socket is always exposed to userspace once SCTP_DBG_OBJCNT_INC() is incremented, but there is a path where the assumption is not true. In sctp_accept(), sctp_sock_migrate() could fail after sctp_init_sock(). Then, sk_common_release() does not call inet_release() nor sctp_close(). Instead, it calls sk->sk_prot->destroy(). Let's move SCTP_DBG_OBJCNT_DEC() from sctp_close() to sctp_destroy_sock(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Acked-by: Xin Long Link: https://patch.msgid.link/20251023231751.4168390-2-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: prevent possible shift-out-of-bounds in sctp_transport_update_rto

2025-11-24T09:35:50+00:00

[ Upstream commit 1534ff77757e44bcc4b98d0196bc5c0052fce5fa ] syzbot reported a possible shift-out-of-bounds [1] Blamed commit added rto_alpha_max and rto_beta_max set to 1000. It is unclear if some sctp users are setting very large rto_alpha and/or rto_beta. In order to prevent user regression, perform the test at run time. Also add READ_ONCE() annotations as sysctl values can change under us. [1] UBSAN: shift-out-of-bounds in net/sctp/transport.c:509:41 shift exponent 64 is too large for 32-bit type 'unsigned int' CPU: 0 UID: 0 PID: 16704 Comm: syz.2.2320 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120 ubsan_epilogue lib/ubsan.c:233 [inline] __ubsan_handle_shift_out_of_bounds+0x27f/0x420 lib/ubsan.c:494 sctp_transport_update_rto.cold+0x1c/0x34b net/sctp/transport.c:509 sctp_check_transmitted+0x11c4/0x1c30 net/sctp/outqueue.c:1502 sctp_outq_sack+0x4ef/0x1b20 net/sctp/outqueue.c:1338 sctp_cmd_process_sack net/sctp/sm_sideeffect.c:840 [inline] sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1372 [inline] Fixes: b58537a1f562 ("net: sctp: fix permissions for rto_alpha and rto_beta knobs") Reported-by: syzbot+f8c46c8b2b7f6e076e99@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/690c81ae.050a0220.3d0d33.014e.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Cc: Daniel Borkmann Acked-by: Xin Long Link: https://patch.msgid.link/20251106111054.3288127-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: Hold sock lock while iterating over address list

2025-11-13T20:34:38+00:00

[ Upstream commit f1fc201148c7e684c10a72b6a3375597f28d1ef6 ] Move address list traversal in inet_assoc_attr_size() under the sock lock to avoid holding the RCU read lock. Suggested-by: Xin Long Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file") Signed-off-by: Stefan Wiehler Acked-by: Xin Long Link: https://patch.msgid.link/20251028161506.3294376-4-stefan.wiehler@nokia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: Prevent TOCTOU out-of-bounds write

2025-11-13T20:34:38+00:00

[ Upstream commit 95aef86ab231f047bb8085c70666059b58f53c09 ] For the following path not holding the sock lock, sctp_diag_dump() -> sctp_for_each_endpoint() -> sctp_ep_dump() make sure not to exceed bounds in case the address list has grown between buffer allocation (time-of-check) and write (time-of-use). Suggested-by: Kuniyuki Iwashima Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file") Signed-off-by: Stefan Wiehler Reviewed-by: Kuniyuki Iwashima Acked-by: Xin Long Link: https://patch.msgid.link/20251028161506.3294376-3-stefan.wiehler@nokia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: Hold RCU read lock while iterating over address list

2025-11-13T20:34:38+00:00

[ Upstream commit 38f50242bf0f237cdc262308d624d333286ec3c5 ] With CONFIG_PROVE_RCU_LIST=y and by executing $ netcat -l --sctp & $ netcat --sctp localhost & $ ss --sctp one can trigger the following Lockdep-RCU splat(s): WARNING: suspicious RCU usage 6.18.0-rc1-00093-g7f864458e9a6 #5 Not tainted ----------------------------- net/sctp/diag.c:76 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 2 locks held by ss/215: #0: ffff9c740828bec0 (nlk_cb_mutex-SOCK_DIAG){+.+.}-{4:4}, at: __netlink_dump_start+0x84/0x2b0 #1: ffff9c7401d72cd0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: sctp_sock_dump+0x38/0x200 stack backtrace: CPU: 0 UID: 0 PID: 215 Comm: ss Not tainted 6.18.0-rc1-00093-g7f864458e9a6 #5 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x5d/0x90 lockdep_rcu_suspicious.cold+0x4e/0xa3 inet_sctp_diag_fill.isra.0+0x4b1/0x5d0 sctp_sock_dump+0x131/0x200 sctp_transport_traverse_process+0x170/0x1b0 ? __pfx_sctp_sock_filter+0x10/0x10 ? __pfx_sctp_sock_dump+0x10/0x10 sctp_diag_dump+0x103/0x140 __inet_diag_dump+0x70/0xb0 netlink_dump+0x148/0x490 __netlink_dump_start+0x1f3/0x2b0 inet_diag_handler_cmd+0xcd/0x100 ? __pfx_inet_diag_dump_start+0x10/0x10 ? __pfx_inet_diag_dump+0x10/0x10 ? __pfx_inet_diag_dump_done+0x10/0x10 sock_diag_rcv_msg+0x18e/0x320 ? __pfx_sock_diag_rcv_msg+0x10/0x10 netlink_rcv_skb+0x4d/0x100 netlink_unicast+0x1d7/0x2b0 netlink_sendmsg+0x203/0x450 ____sys_sendmsg+0x30c/0x340 ___sys_sendmsg+0x94/0xf0 __sys_sendmsg+0x83/0xf0 do_syscall_64+0xbb/0x390 entry_SYSCALL_64_after_hwframe+0x77/0x7f ... Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file") Signed-off-by: Stefan Wiehler Reviewed-by: Kuniyuki Iwashima Acked-by: Xin Long Link: https://patch.msgid.link/20251028161506.3294376-2-stefan.wiehler@nokia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: avoid NULL dereference when chunk data buffer is missing

2025-10-29T13:08:55+00:00

[ Upstream commit 441f0647f7673e0e64d4910ef61a5fb8f16bfb82 ] chunk->skb pointer is dereferenced in the if-block where it's supposed to be NULL only. chunk->skb can only be NULL if chunk->head_skb is not. Check for frag_list instead and do it just before replacing chunk->skb. We're sure that otherwise chunk->skb is non-NULL because of outer if() condition. Fixes: 90017accff61 ("sctp: Add GSO support") Signed-off-by: Alexey Simakov Acked-by: Marcelo Ricardo Leitner Link: https://patch.msgid.link/20251021130034.6333-1-bigalex934@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: Fix MAC comparison to be constant-time

2025-10-19T14:33:53+00:00

commit dd91c79e4f58fbe2898dac84858033700e0e99fb upstream. To prevent timing attacks, MACs need to be compared in constant time. Use the appropriate helper function for this. Fixes: bbd0d59809f9 ("[SCTP]: Implement the receive and verification of AUTH chunk") Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers Link: https://patch.msgid.link/20250818205426.30222-3-ebiggers@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/sctp: fix a null dereference in sctp_disposition sctp_sf_do_5_1D_ce()

2025-10-19T14:33:40+00:00

[ Upstream commit 2f3119686ef50319490ccaec81a575973da98815 ] If new_asoc->peer.adaptation_ind=0 and sctp_ulpevent_make_authkey=0 and sctp_ulpevent_make_authkey() returns 0, then the variable ai_ev remains zero and the zero will be dereferenced in the sctp_ulpevent_free() function. Signed-off-by: Alexandr Sapozhnikov Acked-by: Xin Long Fixes: 30f6ebf65bc4 ("sctp: add SCTP_AUTH_NO_AUTH type for AUTHENTICATION_EVENT") Link: https://patch.msgid.link/20251002091448.11-1-alsp705@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: initialize more fields in sctp_v6_from_sk()

2025-09-04T13:31:51+00:00

[ Upstream commit 2e8750469242cad8f01f320131fd5a6f540dbb99 ] syzbot found that sin6_scope_id was not properly initialized, leading to undefined behavior. Clear sin6_scope_id and sin6_flowinfo. BUG: KMSAN: uninit-value in __sctp_v6_cmp_addr+0x887/0x8c0 net/sctp/ipv6.c:649 __sctp_v6_cmp_addr+0x887/0x8c0 net/sctp/ipv6.c:649 sctp_inet6_cmp_addr+0x4f2/0x510 net/sctp/ipv6.c:983 sctp_bind_addr_conflict+0x22a/0x3b0 net/sctp/bind_addr.c:390 sctp_get_port_local+0x21eb/0x2440 net/sctp/socket.c:8452 sctp_get_port net/sctp/socket.c:8523 [inline] sctp_listen_start net/sctp/socket.c:8567 [inline] sctp_inet_listen+0x710/0xfd0 net/sctp/socket.c:8636 __sys_listen_socket net/socket.c:1912 [inline] __sys_listen net/socket.c:1927 [inline] __do_sys_listen net/socket.c:1932 [inline] __se_sys_listen net/socket.c:1930 [inline] __x64_sys_listen+0x343/0x4c0 net/socket.c:1930 x64_sys_call+0x271d/0x3e20 arch/x86/include/generated/asm/syscalls_64.h:51 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Local variable addr.i.i created at: sctp_get_port net/sctp/socket.c:8515 [inline] sctp_listen_start net/sctp/socket.c:8567 [inline] sctp_inet_listen+0x650/0xfd0 net/sctp/socket.c:8636 __sys_listen_socket net/socket.c:1912 [inline] __sys_listen net/socket.c:1927 [inline] __do_sys_listen net/socket.c:1932 [inline] __se_sys_listen net/socket.c:1930 [inline] __x64_sys_listen+0x343/0x4c0 net/socket.c:1930 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+e69f06a0f30116c68056@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/68adc0a2.050a0220.37038e.00c4.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Cc: Marcelo Ricardo Leitner Acked-by: Xin Long Link: https://patch.msgid.link/20250826141314.1802610-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin