CVE-2024-44935

Public on

Last Modified: UTC

Description

The CVE Program describes this issue as:

In the Linux kernel, the following vulnerability has been resolved: sctp: Fix null-ptr-deref in reuseport_add_sock(). syzbot reported a null-ptr-deref while accessing sk2->sk_reuseport_cb in reuseport_add_sock(). [0] The repro first creates a listener with SO_REUSEPORT. Then, it creates another listener on the same port and concurrently closes the first listener. The second listen() calls reuseport_add_sock() with the first listener as sk2, where sk2->sk_reuseport_cb is not expected to be cleared concurrently, but the close() does clear it by reuseport_detach_sock(). The problem is SCTP does not properly synchronise reuseport_alloc(), reuseport_add_sock(), and reuseport_detach_sock(). The caller of reuseport_alloc() and reuseport_{add,detach}_sock() must provide synchronisation for sockets that are classified into the same reuseport group. Otherwise, such sockets form multiple identical reuseport groups, and all groups except one would be silently dead. 1. Two sockets call listen() concurrently 2. No socket in the same group found in sctp_ep_hashtable[] 3. Two sockets call reuseport_alloc() and form two reuseport groups 4. Only one group hit first in __sctp_rcv_lookup_endpoint() receives incoming packets Also, the reported null-ptr-deref could occur. TCP/UDP guarantees that would not happen by holding the hash bucket lock. Let's apply the locking strategy to __sctp_hash_endpoint() and __sctp_unhash_endpoint(). [0]: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] CPU: 1 UID: 0 PID: 10230 Comm: syz-executor119 Not tainted 6.10.0-syzkaller-12585-g301927d2d2eb #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024 RIP: 0010:reuseport_add_sock+0x27e/0x5e0 net/core/sock_reuseport.c:350 Code: 00 0f b7 5d 00 bf 01 00 00 00 89 de e8 1b a4 ff f7 83 fb 01 0f 85 a3 01 00 00 e8 6d a0 ff f7 49 8d 7e 12 48 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 4b 02 00 00 41 0f b7 5e 12 49 8d 7e 14 RSP: 0018:ffffc9000b947c98 EFLAGS: 00010202 RAX: 0000000000000002 RBX: ffff8880252ddf98 RCX: ffff888079478000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000012 RBP: 0000000000000001 R08: ffffffff8993e18d R09: 1ffffffff1fef385 R10: dffffc0000000000 R11: fffffbfff1fef386 R12: ffff8880252ddac0 R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f24e45b96c0(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffcced5f7b8 CR3: 00000000241be000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> __sctp_hash_endpoint net/sctp/input.c:762 [inline] sctp_hash_endpoint+0x52a/0x600 net/sctp/input.c:790 sctp_listen_start net/sctp/socket.c:8570 [inline] sctp_inet_listen+0x767/0xa20 net/sctp/socket.c:8625 __sys_listen_socket net/socket.c:1883 [inline] __sys_listen+0x1b7/0x230 net/socket.c:1894 __do_sys_listen net/socket.c:1902 [inline] __se_sys_listen net/socket.c:1900 [inline] __x64_sys_listen+0x5a/0x70 net/socket.c:1900 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f24e46039b9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 91 1a 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:00007f24e45b9228 EFLAGS: 00000246 ORIG_RAX: 0000000000000032 RAX: ffffffffffffffda RBX: 00007f24e468e428 RCX: 00007f24e46039b9 RDX: 00007f24e46039b9 RSI: 0000000000000003 RDI: 0000000000000004 RBP: 00007f24e468e420 R08: 00007f24e45b96c0 R09: 00007f24e45b96c0 R10: 00007f24e45b96c0 R11: 0000000000000246 R12: 00007f24e468e42c R13: ---truncated---

Additional information

  • Bugzilla 2307892: kernel: sctp: Fix null-ptr-deref in reuseport_add_sock().
  • CWE-476: NULL Pointer Dereference
  • FAQ: Frequently asked questions about CVE-2024-44935

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

CVSS v3 Score Breakdown
Red HatNVD

CVSS v3 Base Score

5.5

5.5

Attack Vector

Local

Local

Attack Complexity

Low

Low

Privileges Required

Low

Low

User Interaction

None

None

Scope

Unchanged

Unchanged

Confidentiality Impact

None

None

Integrity Impact

None

None

Availability Impact

High

High

CVSS v3 Vector

Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?

  • "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
  • "Affected" means that our Analysis Team has determined that this product is affected by this vulnerability and might release a fix to address this in the near future.

What can I do if my product is listed as "Will not fix"?

A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
  • Apply a mitigation (if one exists).
  • Open a support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Apply a mitigation (if one exists).
  • Open a support case to request a prioritization of releasing a fix for this vulnerability.
  • Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

A mitigation is an action that can be taken to reduce the impact of a security vulnerability, without deploying any fixes.

I have a Red Hat product but it is not in the above list, is it affected?

The listed products were found to include one or more of the components that this vulnerability affects. These products underwent a thorough evaluation to determine their affectedness by this vulnerability. Note that layered products (such as container-based offerings) that consume affected components from any of the products listed in this table may be affected and are not represented.

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our Red Hat Vulnerability Scanner Certification program.

My product is listed as "Out of Support Scope". What does this mean?

When a product is listed as "Out of Support Scope", it means a vulnerability with the impact level assigned to this CVE is no longer covered by its current support lifecycle phase. The product has been identified to contain the impacted component, but analysis to determine whether it is affected or not by this vulnerability was not performed. The product should be assumed to be affected. Customers are advised to apply any mitigation options documented on this page, consider removing or disabling the impacted component, or upgrade to a supported version of the product that has an update available.

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