CVE-2024-36904: tcp: Use refcount_inc_not_zero() in tcp_twsk_unique().
In the Linux kernel, the following vulnerability has been resolved:
tcp: Use refcountincnotzero() in tcptwskunique().
Anderson Nascimento reported a use-after-free splat in tcptwskunique() with nice analysis.
Since commit ec94c2696f0b ("tcp/dccp: avoid one atomic operation for timewait hashdance"), inettwskhashdance() sets TIME-WAIT socket's skrefcnt after putting it into ehash and releasing the bucket lock.
Thus, there is a small race window where other threads could try to reuse the port during connect() and call sockhold() in tcptwskunique() for the TIME-WAIT socket with zero refcnt.
If that happens, the refcnt taken by tcptwskunique() is overwritten and sockput() will cause underflow, triggering a real use-after-free somewhere else.
To avoid the use-after-free, we need to use refcountincnotzero() in tcptwskunique() and give up on reusing the port if it returns false.
[0]: refcountt: addition on 0; use-after-free. WARNING: CPU: 0 PID: 1039313 at lib/refcount.c:25 refcountwarnsaturate+0xe5/0x110 CPU: 0 PID: 1039313 Comm: trigger Not tainted 6.8.6-200.fc39.x8664 #1 Hardware name: VMware, Inc. VMware20,1/440BX Desktop Reference Platform, BIOS VMW201.00V.21805430.B64.2305221830 05/22/2023 RIP: 0010:refcountwarnsaturate+0xe5/0x110 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 <0f> 0b c3 cc cc cc cc 48 c7 c7 50 8f b7 82 c6 05 7a 13 ea 01 01 e8 RSP: 0018:ffffc90006b43b60 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff888009bb3ef0 RCX: 0000000000000027 RDX: ffff88807be218c8 RSI: 0000000000000001 RDI: ffff88807be218c0 RBP: 0000000000069d70 R08: 0000000000000000 R09: ffffc90006b439f0 R10: ffffc90006b439e8 R11: 0000000000000003 R12: ffff8880029ede84 R13: 0000000000004e20 R14: ffffffff84356dc0 R15: ffff888009bb3ef0 FS: 00007f62c10926c0(0000) GS:ffff88807be00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020ccb000 CR3: 000000004628c005 CR4: 0000000000f70ef0 PKRU: 55555554 Call Trace: <TASK> ? refcountwarnsaturate+0xe5/0x110 ? warn+0x81/0x130 ? refcountwarnsaturate+0xe5/0x110 ? reportbug+0x171/0x1a0 ? refcountwarnsaturate+0xe5/0x110 ? handlebug+0x3c/0x80 ? excinvalidop+0x17/0x70 ? asmexcinvalidop+0x1a/0x20 ? refcountwarnsaturate+0xe5/0x110 tcptwskunique+0x186/0x190 inetcheckestablished+0x176/0x2d0 inethashconnect+0x74/0x7d0 ? pfxinetcheckestablished+0x10/0x10 tcpv4connect+0x278/0x530 inetstreamconnect+0x10f/0x3d0 inetstreamconnect+0x3a/0x60 sysconnect+0xa8/0xd0 x64sysconnect+0x18/0x20 dosyscall64+0x83/0x170 entrySYSCALL64afterhwframe+0x78/0x80 RIP: 0033:0x7f62c11a885d 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 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a3 45 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007f62c1091e58 EFLAGS: 00000296 ORIGRAX: 000000000000002a RAX: ffffffffffffffda RBX: 0000000020ccb004 RCX: 00007f62c11a885d RDX: 0000000000000010 RSI: 0000000020ccb000 RDI: 0000000000000003 RBP: 00007f62c1091e90 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 00007f62c10926c0 R13: ffffffffffffff88 R14: 0000000000000000 R15: 00007ffe237885b0 </TASK>
Other sources
In the Linux kernel, the following vulnerability has been resolved:
tcp: Use refcountincnotzero() in tcptwskunique().
The Linux kernel CVE team has assigned CVE-2024-36904 to this issue.
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2024053036-CVE-2024-36904-2273@gregkh/T
— Red Hat
Linux Kernel could allow a local authenticated attacker to gain elevated privileges, caused by a use-after-free in the TCP protocol. An attacker could exploit this vulnerability to gain elevated privileges on the system.
— IBM
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2024-36904?
CVE-2024-36904 is a high-severity vulnerability due to a use-after-free condition in the Linux kernel.
How do I fix CVE-2024-36904?
To fix CVE-2024-36904, update your Linux kernel to one of the remedied versions specified, such as 4.19.314 or 5.4.276.
What versions of the Linux kernel are affected by CVE-2024-36904?
CVE-2024-36904 affects multiple Linux kernel versions prior to 4.19.314, 5.4.276, 5.10.217, 5.15.159, 6.1.91, and others.
Who reported the CVE-2024-36904 vulnerability?
The CVE-2024-36904 vulnerability was reported by Anderson Nascimento.
What specific function is impacted in CVE-2024-36904?
CVE-2024-36904 affects the tcp_twsk_unique() function in the Linux kernel.