CVE-2025-38181
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- CVE-2025-38181
CVE Details
| Release Date: | 2025-07-04 | |
| Impact: | Moderate | What is this? |
Description
In the Linux kernel, the following vulnerability has been resolved:
calipso: Fix null-ptr-deref in calipso_req_{set,del}attr().
syzkaller reported a null-ptr-deref in sock_omalloc() while allocating
a CALIPSO option. [0]
The NULL is of struct sock, which was fetched by sk_to_full_sk() in
calipso_req_setattr().
Since commit a1a5344ddbe8 ("tcp: avoid two atomic ops for syncookies"),
reqsk->rsk_listener could be NULL when SYN Cookie is returned to its
client, as hinted by the leading SYN Cookie log.
Here are 3 options to fix the bug:
1) Return 0 in calipso_req_setattr()
2) Return an error in calipso_req_setattr()
3) Alaways set rsk_listener
1) is no go as it bypasses LSM, but 2) effectively disables SYN Cookie
for CALIPSO. 3) is also no go as there have been many efforts to reduce
atomic ops and make TCP robust against DDoS. See also commit 3b24d854cb35
("tcp/dccp: do not touch listener sk_refcnt under synflood").
As of the blamed commit, SYN Cookie already did not need refcounting,
and no one has stumbled on the bug for 9 years, so no CALIPSO user will
care about SYN Cookie.
Let's return an error in calipso_req_setattr() and calipso_req_delattr()
in the SYN Cookie case.
This can be reproduced by [1] on Fedora and now connect() of nc times out.
[0]:
TCP: request_sock_TCPv6: Possible SYN flooding on port [::]:20002. Sending cookies.
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
CPU: 3 UID: 0 PID: 12262 Comm: syz.1.2611 Not tainted 6.14.0 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
RIP: 0010:read_pnet include/net/net_namespace.h:406 [inline]
RIP: 0010:sock_net include/net/sock.h:655 [inline]
RIP: 0010:sock_kmalloc+0x35/0x170 net/core/sock.c:2806
Code: 89 d5 41 54 55 89 f5 53 48 89 fb e8 25 e3 c6 fd e8 f0 91 e3 00 48 8d 7b 30 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 26 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b
RSP: 0018:ffff88811af89038 EFLAGS: 00010216
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffff888105266400
RDX: 0000000000000006 RSI: ffff88800c890000 RDI: 0000000000000030
RBP: 0000000000000050 R08: 0000000000000000 R09: ffff88810526640e
R10: ffffed1020a4cc81 R11: ffff88810526640f R12: 0000000000000000
R13: 0000000000000820 R14: ffff888105266400 R15: 0000000000000050
FS: 00007f0653a07640(0000) GS:ffff88811af80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f863ba096f4 CR3: 00000000163c0005 CR4: 0000000000770ef0
PKRU: 80000000
Call Trace:
See more information about CVE-2025-38181 from MITRE CVE dictionary and NIST NVD
NOTE: The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 metrics
| Base Score: | 7.0 |
| Vector String: | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H |
| Version: | 3.1 |
| Attack Vector: | Local |
| Attack Complexity: | High |
| Privileges Required: | Low |
| User Interaction: | None |
| Scope: | Unchanged |
| Confidentiality Impact: | High |
| Integrity Impact: | High |
| Availability Impact: | High |
Errata information
| Platform | Errata | Release Date |
| Oracle Linux version 10 (kernel-uek) | ELSA-2025-20551 | 2025-09-08 |
| Oracle Linux version 8 (kernel-uek) | ELSA-2025-20552 | 2025-09-08 |
| Oracle Linux version 9 (kernel-uek) | ELSA-2025-20551 | 2025-09-08 |
| Oracle Linux version 9 (kernel-uek) | ELSA-2025-20552 | 2025-09-08 |
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