CVE-2024-36904

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> tcp: Use refcount_inc_not_zero() in tcp_twsk_unique().<br /> <br /> Anderson Nascimento reported a use-after-free splat in tcp_twsk_unique()<br /> with nice analysis.<br /> <br /> Since commit ec94c2696f0b ("tcp/dccp: avoid one atomic operation for<br /> timewait hashdance"), inet_twsk_hashdance() sets TIME-WAIT socket&amp;#39;s<br /> sk_refcnt after putting it into ehash and releasing the bucket lock.<br /> <br /> Thus, there is a small race window where other threads could try to<br /> reuse the port during connect() and call sock_hold() in tcp_twsk_unique()<br /> for the TIME-WAIT socket with zero refcnt.<br /> <br /> If that happens, the refcnt taken by tcp_twsk_unique() is overwritten<br /> and sock_put() will cause underflow, triggering a real use-after-free<br /> somewhere else.<br /> <br /> To avoid the use-after-free, we need to use refcount_inc_not_zero() in<br /> tcp_twsk_unique() and give up on reusing the port if it returns false.<br /> <br /> [0]:<br /> refcount_t: addition on 0; use-after-free.<br /> WARNING: CPU: 0 PID: 1039313 at lib/refcount.c:25 refcount_warn_saturate+0xe5/0x110<br /> CPU: 0 PID: 1039313 Comm: trigger Not tainted 6.8.6-200.fc39.x86_64 #1<br /> Hardware name: VMware, Inc. VMware20,1/440BX Desktop Reference Platform, BIOS VMW201.00V.21805430.B64.2305221830 05/22/2023<br /> RIP: 0010:refcount_warn_saturate+0xe5/0x110<br /> Code: 42 8e ff 0f 0b c3 cc cc cc cc 80 3d aa 13 ea 01 00 0f 85 5e ff ff ff 48 c7 c7 f8 8e b7 82 c6 05 96 13 ea 01 01 e8 7b 42 8e ff 0b c3 cc cc cc cc 48 c7 c7 50 8f b7 82 c6 05 7a 13 ea 01 01 e8<br /> RSP: 0018:ffffc90006b43b60 EFLAGS: 00010282<br /> RAX: 0000000000000000 RBX: ffff888009bb3ef0 RCX: 0000000000000027<br /> RDX: ffff88807be218c8 RSI: 0000000000000001 RDI: ffff88807be218c0<br /> RBP: 0000000000069d70 R08: 0000000000000000 R09: ffffc90006b439f0<br /> R10: ffffc90006b439e8 R11: 0000000000000003 R12: ffff8880029ede84<br /> R13: 0000000000004e20 R14: ffffffff84356dc0 R15: ffff888009bb3ef0<br /> FS: 00007f62c10926c0(0000) GS:ffff88807be00000(0000) knlGS:0000000000000000<br /> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br /> CR2: 0000000020ccb000 CR3: 000000004628c005 CR4: 0000000000f70ef0<br /> PKRU: 55555554<br /> Call Trace:<br /> <br /> ? refcount_warn_saturate+0xe5/0x110<br /> ? __warn+0x81/0x130<br /> ? refcount_warn_saturate+0xe5/0x110<br /> ? report_bug+0x171/0x1a0<br /> ? refcount_warn_saturate+0xe5/0x110<br /> ? handle_bug+0x3c/0x80<br /> ? exc_invalid_op+0x17/0x70<br /> ? asm_exc_invalid_op+0x1a/0x20<br /> ? refcount_warn_saturate+0xe5/0x110<br /> tcp_twsk_unique+0x186/0x190<br /> __inet_check_established+0x176/0x2d0<br /> __inet_hash_connect+0x74/0x7d0<br /> ? __pfx___inet_check_established+0x10/0x10<br /> tcp_v4_connect+0x278/0x530<br /> __inet_stream_connect+0x10f/0x3d0<br /> inet_stream_connect+0x3a/0x60<br /> __sys_connect+0xa8/0xd0<br /> __x64_sys_connect+0x18/0x20<br /> do_syscall_64+0x83/0x170<br /> entry_SYSCALL_64_after_hwframe+0x78/0x80<br /> RIP: 0033:0x7f62c11a885d<br /> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 3d 01 f0 ff ff 73 01 c3 48 8b 0d a3 45 0c 00 f7 d8 64 89 01 48<br /> RSP: 002b:00007f62c1091e58 EFLAGS: 00000296 ORIG_RAX: 000000000000002a<br /> RAX: ffffffffffffffda RBX: 0000000020ccb004 RCX: 00007f62c11a885d<br /> RDX: 0000000000000010 RSI: 0000000020ccb000 RDI: 0000000000000003<br /> RBP: 00007f62c1091e90 R08: 0000000000000000 R09: 0000000000000000<br /> R10: 0000000000000000 R11: 0000000000000296 R12: 00007f62c10926c0<br /> R13: ffffffffffffff88 R14: 0000000000000000 R15: 00007ffe237885b0<br />