tcp: Fix refcnt handling in __inet_hash_connect().
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 2 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-200.
Summary
In the Linux kernel, the following vulnerability has been resolved: tcp: Fix refcnt handling in __inet_hash_connect(). syzbot reported a warning in sk_nulls_del_node_init_rcu(). The commit 66b60b0c8c4a ("dccp/tcp: Unhash sk from ehash for tb2 alloc failure after check_estalblished().") tried to fix an issue that an unconnected socket occupies an ehash entry when bhash2 allocation fails. In such a case, we need to revert changes done by check_established(), which does not hold refcnt when inserting socket into ehash. So, to revert the change, we need to __sk_nulls_add_node_rcu() instead of sk_nulls_add_node_rcu(). Otherwise, sock_put() will cause refcnt underflow and leak the socket. [0]: WARNING: CPU: 0 PID: 23948 at include/net/sock.h:799 sk_nulls_del_node_init_rcu+0x166/0x1a0 include/net/sock.h:799 Modules linked in: CPU: 0 PID: 23948 Comm: syz-executor.2 Not tainted 6.8.0-rc6-syzkaller-00159-gc055fc00c07b #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 RIP: 0010:sk_nulls_del_node_init_rcu+0x166/0x1a0 include/net/sock.h:799 Code: e8 7f 71 c6 f7 83 fb 02 7c 25 e8 35 6d c6 f7 4d 85 f6 0f 95 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc e8 1b 6d c6 f7 90 <0f> 0b 90 eb b2 e8 10 6d c6 f7 4c 89 e7 be 04 00 00 00 e8 63 e7 d2 RSP: 0018:ffffc900032d7848 EFLAGS: 00010246 RAX: ffffffff89cd0035 RBX: 0000000000000001 RCX: 0000000000040000 RDX: ffffc90004de1000 RSI: 000000000003ffff RDI: 0000000000040000 RBP: 1ffff1100439ac26 R08: ffffffff89ccffe3 R09: 1ffff1100439ac28 R10: dffffc0000000000 R11: ffffed100439ac29 R12: ffff888021cd6140 R13: dffffc0000000000 R14: ffff88802a9bf5c0 R15: ffff888021cd6130 FS: 00007f3b823f16c0(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3b823f0ff8 CR3: 000000004674a000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> __inet_hash_connect+0x140f/0x20b0 net/ipv4/inet_hashtables.c:1139 dccp_v6_connect+0xcb9/0x1480 net/dccp/ipv6.c:956 __inet_stream_connect+0x262/0xf30 net/ipv4/af_inet.c:678 inet_stream_connect+0x65/0xa0 net/ipv4/af_inet.c:749 __sys_connect_file net/socket.c:2048 [inline] __sys_connect+0x2df/0x310 net/socket.c:2065 __do_sys_connect net/socket.c:2075 [inline] __se_sys_connect net/socket.c:2072 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:2072 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 RIP: 0033:0x7f3b8167dda9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3b823f10c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 00007f3b817abf80 RCX: 00007f3b8167dda9 RDX: 000000000000001c RSI: 0000000020000040 RDI: 0000000000000003 RBP: 00007f3b823f1120 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 000000000000000b R14: 00007f3b817abf80 R15: 00007ffd3beb57b8 </TASK>
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 6.1.80 to before 6.1.83; 6.6.19 to before 6.6.23; 6.7.7 to before 6.7.11 | 6.1.83, 6.6.23, 6.7.11 | Patch available | CNA |
| Linux | Linux | 6.8 and later | 6.1.83, 6.6.23, 6.7.11, 6.8.2, 6.9 | Patch available | CNA |
- Linux VendorLinux Affected 6.1.80 to before 6.1.83; 6.6.19 to before 6.6.23; 6.7.7 to before 6.7.11 Fixed in 6.1.83, 6.6.23, 6.7.11 Patch available CNA
- Linux VendorLinux Affected 6.8 and later Fixed in 6.1.83, 6.6.23, 6.7.11, 6.8.2, 6.9 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 6.1.80 to before 6.1.83; 6.6.19 to before 6.6.23; 6.7.7 to before 6.7.11; 6.8 to before 6.8.2 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 6.1.80 to before 6.1.83; 6.6.19 to before 6.6.23; 6.7.7 to before 6.7.11; 6.8 to before 6.8.2 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.83, 6.6.23, 6.7.11
- Fix · CNA Linux (Linux) Fixed in 6.1.83, 6.6.23, 6.7.11, 6.8.2, 6.9
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
Not affected: 2 products
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2024-26864
- 2026-10-03 Alias added: GHSA-vffh-vwhr-v5jp
References
Patch 5
- https://git.kernel.org/stable/c/86d9b040421bbd26425f5a3edc226f57ecdecbfe
- https://git.kernel.org/stable/c/856baaa100cd288d3685eedae9a129c996e7e755
- https://git.kernel.org/stable/c/1b20e61d36f490319d3fbdedd410155232ab5190
- https://git.kernel.org/stable/c/ad105cde6b261b8b05ec872fe7d1987417d7fe5a
- https://git.kernel.org/stable/c/04d9d1fc428ac9f581d55118d67e0cb546701feb
More Linux Kernel vulnerabilities
- TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
- TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
- TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
Sources
- CVE-2024-26864 · CVE Program
- CVE-2024-26864 · NVD
- FIRST EPSS
- GHSA-vffh-vwhr-v5jp · GitHub Advisory Database · CC BY 4.0
- CVE-2024-26864 · Red Hat security data · CC BY 4.0
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