CVE-2024-45012

In the Linux kernel, the following vulnerability has been resolved:

nouveau/firmware: use dma non-coherent allocator

Currently, enabling SG_DEBUG in the kernel will cause nouveau to hit a BUG() on startup, when the iommu is enabled:

kernel BUG at include/linux/scatterlist.h:187! invalid opcode: 0000 [#1] PREEMPT SMP NOPTI CPU: 7 PID: 930 Comm: (udev-worker) Not tainted 6.9.0-rc3Lyude-Test+ #30 Hardware name: MSI MS-7A39/A320M GAMING PRO (MS-7A39), BIOS 1.I0 01/22/2019 RIP: 0010:sg_init_one+0x85/0xa0 Code: 69 88 32 01 83 e1 03 f6 c3 03 75 20 a8 01 75 1e 48 09 cb 41 89 54 24 08 49 89 1c 24 41 89 6c 24 0c 5b 5d 41 5c e9 7b b9 88 00 <0f> 0b 0f 0b 0f 0b 48 8b 05 5e 46 9a 01 eb b2 66 66 2e 0f 1f 84 00 RSP: 0018:ffffa776017bf6a0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffffa77600d87000 RCX: 000000000000002b RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffa77680d87000 RBP: 000000000000e000 R08: 0000000000000000 R09: 0000000000000000 R10: ffff98f4c46aa508 R11: 0000000000000000 R12: ffff98f4c46aa508 R13: ffff98f4c46aa008 R14: ffffa77600d4a000 R15: ffffa77600d4a018 FS: 00007feeb5aae980(0000) GS:ffff98f5c4dc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f22cb9a4520 CR3: 00000001043ba000 CR4: 00000000003506f0 Call Trace: ? die+0x36/0x90 ? do_trap+0xdd/0x100 ? sg_init_one+0x85/0xa0 ? do_error_trap+0x65/0x80 ? sg_init_one+0x85/0xa0 ? exc_invalid_op+0x50/0x70 ? sg_init_one+0x85/0xa0 ? asm_exc_invalid_op+0x1a/0x20 ? sg_init_one+0x85/0xa0 nvkm_firmware_ctor+0x14a/0x250 [nouveau] nvkm_falcon_fw_ctor+0x42/0x70 [nouveau] ga102_gsp_booter_ctor+0xb4/0x1a0 [nouveau] r535_gsp_oneinit+0xb3/0x15f0 [nouveau] ? srso_return_thunk+0x5/0x5f ? srso_return_thunk+0x5/0x5f ? nvkm_udevice_new+0x95/0x140 [nouveau] ? srso_return_thunk+0x5/0x5f ? srso_return_thunk+0x5/0x5f ? ktime_get+0x47/0xb0

Fix this by using the non-coherent allocator instead, I think there might be a better answer to this, but it involve ripping up some of APIs using sg lists.

Weakness

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.

Affected Software

Extended Description

Code frequently has to work with limited resources, so programmers must be careful to ensure that resources are not consumed too quickly, or too easily. Without use of quotas, resource limits, or other protection mechanisms, it can be easy for an attacker to consume many resources by rapidly making many requests, or causing larger resources to be used than is needed. When too many resources are allocated, or if a single resource is too large, then it can prevent the code from working correctly, possibly leading to a denial of service.

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”

• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

• Mitigation of resource exhaustion attacks requires that the target system either:

• The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

• The second solution can be difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply requires more resources on the part of the attacker.

• If the program must fail, ensure that it fails gracefully (fails closed). There may be a temptation to simply let the program fail poorly in cases such as low memory conditions, but an attacker may be able to assert control before the software has fully exited. Alternately, an uncontrolled failure could cause cascading problems with other downstream components; for example, the program could send a signal to a downstream process so the process immediately knows that a problem has occurred and has a better chance of recovery.

• Ensure that all failures in resource allocation place the system into a safe posture.

• Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems.

• When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users.

• Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/125.html
• https://cwe.mitre.org/data/definitions/130.html
• https://cwe.mitre.org/data/definitions/147.html
• https://cwe.mitre.org/data/definitions/197.html
• https://cwe.mitre.org/data/definitions/229.html
• https://cwe.mitre.org/data/definitions/230.html
• https://cwe.mitre.org/data/definitions/231.html
• https://cwe.mitre.org/data/definitions/469.html
• https://cwe.mitre.org/data/definitions/482.html
• https://cwe.mitre.org/data/definitions/486.html
• https://cwe.mitre.org/data/definitions/487.html
• https://cwe.mitre.org/data/definitions/488.html
• https://cwe.mitre.org/data/definitions/489.html
• https://cwe.mitre.org/data/definitions/490.html
• https://cwe.mitre.org/data/definitions/491.html
• https://cwe.mitre.org/data/definitions/493.html
• https://cwe.mitre.org/data/definitions/494.html
• https://cwe.mitre.org/data/definitions/495.html
• https://cwe.mitre.org/data/definitions/496.html
• https://cwe.mitre.org/data/definitions/528.html

References

• https://git.kernel.org/stable/c/57ca481fca97ca4553e8c85d6a94baf4cb40c40e
• https://git.kernel.org/stable/c/9b340aeb26d50e9a9ec99599e2a39b035fac978e
• https://git.kernel.org/stable/c/cc29c5546c6a373648363ac49781f1d74b530707