CVE-2024-53124: In the Linux kernel, the following vulnerability has been resolved:  net: fix data-races around sk->sk_forward_alloc  Syzkaller reported this warning:  ------------[ cut here ]------------  WARNING: CPU: 0 PID: 16 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x1c5/0x1e0  Modules linked in:  CPU: 0 UID: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.12.0-rc5 #26  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014  RIP: 0010:inet_sock_destruct+0x1c5/0x1e0  Code: 24 12 4c 89 e2 5b 48 c7 c7 98 ec bb 82 41 5c e9 d1 18 17 ff 4c 89 e6 5b 48 c7 c7 d0 ec bb 82 41 5c e9 bf 18 17 ff 0f 0b eb 83 <0f> 0b eb 97 0f 0b eb 87 0f 0b e9 68 ff ff ff 66 66 2e 0f 1f 84 00  RSP: 0018:ffffc9000008bd90 EFLAGS: 00010206  RAX: 0000000000000300 RBX: ffff88810b172a90 RCX: 0000000000000007  RDX: 0000000000000002 RSI: 0000000000000300 RDI: ffff88810b172a00  RBP: ffff88810b172a00 R08: ffff888104273c00 R09: 0000000000100007  R10: 0000000000020000 R11: 0000000000000006 R12: ffff88810b172a00  R13: 0000000000000004 R14: 0000000000000000 R15: ffff888237c31f78  FS:  0000000000000000(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033  CR2: 00007ffc63fecac8 CR3: 000000000342e000 CR4: 00000000000006f0  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400  Call Trace:   <TASK>   ? __warn+0x88/0x130   ? inet_sock_destruct+0x1c5/0x1e0   ? report_bug+0x18e/0x1a0   ? handle_bug+0x53/0x90   ? exc_invalid_op+0x18/0x70   ? asm_exc_invalid_op+0x1a/0x20   ? inet_sock_destruct+0x1c5/0x1e0   __sk_destruct+0x2a/0x200   rcu_do_batch+0x1aa/0x530   ? rcu_do_batch+0x13b/0x530   rcu_core+0x159/0x2f0   handle_softirqs+0xd3/0x2b0   ? __pfx_smpboot_thread_fn+0x10/0x10   run_ksoftirqd+0x25/0x30   smpboot_thread_fn+0xdd/0x1d0   kthread+0xd3/0x100   ? __pfx_kthread+0x10/0x10   ret_from_fork+0x34/0x50   ? __pfx_kthread+0x10/0x10   ret_from_fork_asm+0x1a/0x30   </TASK>  ---[ end trace 0000000000000000 ]---  Its possible that two threads call tcp_v6_do_rcv()/sk_forward_alloc_add() concurrently when sk->sk_state == TCP_LISTEN with sk->sk_lock unlocked, which triggers a data-race around sk->sk_forward_alloc: tcp_v6_rcv     tcp_v6_do_rcv         skb_clone_and_charge_r             sk_rmem_schedule                 __sk_mem_schedule                     sk_forward_alloc_add()             skb_set_owner_r                 sk_mem_charge                     sk_forward_alloc_add()         __kfree_skb             skb_release_all                 skb_release_head_state                     sock_rfree                         sk_mem_uncharge                             sk_forward_alloc_add()                             sk_mem_reclaim                                 // set local var reclaimable                                 __sk_mem_reclaim                                     sk_forward_alloc_add()  In this syzkaller testcase, two threads call tcp_v6_do_rcv() with skb->truesize=768, the sk_forward_alloc changes like this:  (cpu 1)             | (cpu 2)             | sk_forward_alloc  ...                 | ...                 | 0  __sk_mem_schedule() |                     | +4096 = 4096                      | __sk_mem_schedule() | +4096 = 8192  sk_mem_charge()     |                     | -768  = 7424                      | sk_mem_charge()     | -768  = 6656  ...                 |    ...              |  sk_mem_uncharge()   |                     | +768  = 7424  reclaimable=7424    |                     |                      | sk_mem_uncharge()   | +768  = 8192                      | reclaimable=8192    |  __sk_mem_reclaim()  |                     | -4096 = 4096                      | __sk_mem_reclaim()  | -8192 = -4096 != 0  The skb_clone_and_charge_r() should not be called in tcp_v6_do_rcv() when sk->sk_state is TCP_LISTEN, it happens later in tcp_v6_syn_recv_sock(). Fix the same issue in dccp_v6_do_rcv().