From: Davide Caratti dcaratti@redhat.com
when MPTCP server accepts an incoming connection, it clones its listener socket. However, the pointer to 'inet_opt' for the new socket has the same value as the original one: as a consequence, on program exit it's possible to observe the following splat:
BUG: KASAN: double-free in inet_sock_destruct+0x54f/0x8b0 Free of addr ffff888485950880 by task swapper/25/0
CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Not tainted 6.8.0-rc1+ #609 Hardware name: Supermicro SYS-6027R-72RF/X9DRH-7TF/7F/iTF/iF, BIOS 3.0 07/26/2013 Call Trace: <IRQ> dump_stack_lvl+0x32/0x50 print_report+0xca/0x620 kasan_report_invalid_free+0x64/0x90 __kasan_slab_free+0x1aa/0x1f0 kfree+0xed/0x2e0 inet_sock_destruct+0x54f/0x8b0 __sk_destruct+0x48/0x5b0 rcu_do_batch+0x34e/0xd90 rcu_core+0x559/0xac0 __do_softirq+0x183/0x5a4 irq_exit_rcu+0x12d/0x170 sysvec_apic_timer_interrupt+0x6b/0x80 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x16/0x20 RIP: 0010:cpuidle_enter_state+0x175/0x300 Code: 30 00 0f 84 1f 01 00 00 83 e8 01 83 f8 ff 75 e5 48 83 c4 18 44 89 e8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc fb 45 85 ed <0f> 89 60 ff ff ff 48 c1 e5 06 48 c7 43 18 00 00 00 00 48 83 44 2b RSP: 0018:ffff888481cf7d90 EFLAGS: 00000202 RAX: 0000000000000000 RBX: ffff88887facddc8 RCX: 0000000000000000 RDX: 1ffff1110ff588b1 RSI: 0000000000000019 RDI: ffff88887fac4588 RBP: 0000000000000004 R08: 0000000000000002 R09: 0000000000043080 R10: 0009b02ea273363f R11: ffff88887fabf42b R12: ffffffff932592e0 R13: 0000000000000004 R14: 0000000000000000 R15: 00000022c880ec80 cpuidle_enter+0x4a/0xa0 do_idle+0x310/0x410 cpu_startup_entry+0x51/0x60 start_secondary+0x211/0x270 secondary_startup_64_no_verify+0x184/0x18b </TASK>
Allocated by task 6853: kasan_save_stack+0x1c/0x40 kasan_save_track+0x10/0x30 __kasan_kmalloc+0xa6/0xb0 __kmalloc+0x1eb/0x450 cipso_v4_sock_setattr+0x96/0x360 netlbl_sock_setattr+0x132/0x1f0 selinux_netlbl_socket_post_create+0x6c/0x110 selinux_socket_post_create+0x37b/0x7f0 security_socket_post_create+0x63/0xb0 __sock_create+0x305/0x450 __sys_socket_create.part.23+0xbd/0x130 __sys_socket+0x37/0xb0 __x64_sys_socket+0x6f/0xb0 do_syscall_64+0x83/0x160 entry_SYSCALL_64_after_hwframe+0x6e/0x76
Freed by task 6858: kasan_save_stack+0x1c/0x40 kasan_save_track+0x10/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x12c/0x1f0 kfree+0xed/0x2e0 inet_sock_destruct+0x54f/0x8b0 __sk_destruct+0x48/0x5b0 subflow_ulp_release+0x1f0/0x250 tcp_cleanup_ulp+0x6e/0x110 tcp_v4_destroy_sock+0x5a/0x3a0 inet_csk_destroy_sock+0x135/0x390 tcp_fin+0x416/0x5c0 tcp_data_queue+0x1bc8/0x4310 tcp_rcv_state_process+0x15a3/0x47b0 tcp_v4_do_rcv+0x2c1/0x990 tcp_v4_rcv+0x41fb/0x5ed0 ip_protocol_deliver_rcu+0x6d/0x9f0 ip_local_deliver_finish+0x278/0x360 ip_local_deliver+0x182/0x2c0 ip_rcv+0xb5/0x1c0 __netif_receive_skb_one_core+0x16e/0x1b0 process_backlog+0x1e3/0x650 __napi_poll+0xa6/0x500 net_rx_action+0x740/0xbb0 __do_softirq+0x183/0x5a4
The buggy address belongs to the object at ffff888485950880 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 0 bytes inside of 64-byte region [ffff888485950880, ffff8884859508c0)
The buggy address belongs to the physical page: page:0000000056d1e95e refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888485950700 pfn:0x485950 flags: 0x57ffffc0000800(slab|node=1|zone=2|lastcpupid=0x1fffff) page_type: 0xffffffff() raw: 0057ffffc0000800 ffff88810004c640 ffffea00121b8ac0 dead000000000006 raw: ffff888485950700 0000000000200019 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff888485950780: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff888485950800: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff888485950880: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
^ ffff888485950900: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff888485950980: 00 00 00 00 00 01 fc fc fc fc fc fc fc fc fc fc
Something similar (a refcount underflow) happens with CALIPSO/IPv6. Fix this by duplicating IP / IPv6 options after clone, so that ip{,6}_sock_destruct() doesn't end up freeing the same memory area twice.
Fixes: cf7da0d66cc1 ("mptcp: Create SUBFLOW socket for incoming connections") Cc: stable@vger.kernel.org Signed-off-by: Davide Caratti dcaratti@redhat.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://lore.kernel.org/r/20240223-upstream-net-20240223-misc-fixes-v1-8-162... Signed-off-by: Jakub Kicinski kuba@kernel.org (cherry picked from commit 10048689def7e40a4405acda16fdc6477d4ecc5c) Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org --- Notes: - Conflicts in protocol.c because mptcp_sk_clone() has been renamed to mptcp_sk_clone_init() in commit 7e8b88ec35ee ("mptcp: consolidate passive msk socket initialization") which has not been backported to v5.15 due to a too long list of dependences. --- net/mptcp/protocol.c | 49 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 86bd41a0e187..5db1c0142abb 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2856,8 +2856,50 @@ static struct ipv6_pinfo *mptcp_inet6_sk(const struct sock *sk)
return (struct ipv6_pinfo *)(((u8 *)sk) + offset); } + +static void mptcp_copy_ip6_options(struct sock *newsk, const struct sock *sk) +{ + const struct ipv6_pinfo *np = inet6_sk(sk); + struct ipv6_txoptions *opt; + struct ipv6_pinfo *newnp; + + newnp = inet6_sk(newsk); + + rcu_read_lock(); + opt = rcu_dereference(np->opt); + if (opt) { + opt = ipv6_dup_options(newsk, opt); + if (!opt) + net_warn_ratelimited("%s: Failed to copy ip6 options\n", __func__); + } + RCU_INIT_POINTER(newnp->opt, opt); + rcu_read_unlock(); +} #endif
+static void mptcp_copy_ip_options(struct sock *newsk, const struct sock *sk) +{ + struct ip_options_rcu *inet_opt, *newopt = NULL; + const struct inet_sock *inet = inet_sk(sk); + struct inet_sock *newinet; + + newinet = inet_sk(newsk); + + rcu_read_lock(); + inet_opt = rcu_dereference(inet->inet_opt); + if (inet_opt) { + newopt = sock_kmalloc(newsk, sizeof(*inet_opt) + + inet_opt->opt.optlen, GFP_ATOMIC); + if (newopt) + memcpy(newopt, inet_opt, sizeof(*inet_opt) + + inet_opt->opt.optlen); + else + net_warn_ratelimited("%s: Failed to copy ip options\n", __func__); + } + RCU_INIT_POINTER(newinet->inet_opt, newopt); + rcu_read_unlock(); +} + struct sock *mptcp_sk_clone(const struct sock *sk, const struct mptcp_options_received *mp_opt, struct request_sock *req) @@ -2878,6 +2920,13 @@ struct sock *mptcp_sk_clone(const struct sock *sk, nsk->sk_wait_pending = 0; __mptcp_init_sock(nsk);
+#if IS_ENABLED(CONFIG_MPTCP_IPV6) + if (nsk->sk_family == AF_INET6) + mptcp_copy_ip6_options(nsk, sk); + else +#endif + mptcp_copy_ip_options(nsk, sk); + msk = mptcp_sk(nsk); msk->local_key = subflow_req->local_key; msk->token = subflow_req->token;