CVE-2024-38616

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

wifi: carl9170: re-fix fortified-memset warning

The carl9170_tx_release() function sometimes triggers a fortified-memset warning in my randconfig builds:

In file included from include/linux/string.h:254, from drivers/net/wireless/ath/carl9170/tx.c:40: In function fortify_memset_chk, inlined from carl9170_tx_release at drivers/net/wireless/ath/carl9170/tx.c:283:2, inlined from kref_put at include/linux/kref.h:65:3, inlined from carl9170_tx_put_skb at drivers/net/wireless/ath/carl9170/tx.c:342:9: include/linux/fortify-string.h:493:25: error: call to __write_overflow_field declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning] 493 | __write_overflow_field(p_size_field, size);

Kees previously tried to avoid this by using memset_after(), but it seems this does not fully address the problem. I noticed that the memset_after() here is done on a different part of the union (status) than the original cast was from (rate_driver_data), which may confuse the compiler.

Unfortunately, the memset_after() trick does not work on driver_rates[] because that is part of an anonymous struct, and I could not get struct_group() to do this either. Using two separate memset() calls on the two members does address the warning though.

Weakness

The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.

Affected Software

Extended Description

Limited resources include memory, file system storage, database connection pool entries, and CPU. If an attacker can trigger the allocation of these limited resources, but the number or size of the resources is not controlled, then the attacker could cause a denial of service that consumes all available resources. This would prevent valid users from accessing the product, and it could potentially have an impact on the surrounding environment. For example, a memory exhaustion attack against an application could slow down the application as well as its host operating system. There are at least three distinct scenarios which can commonly lead to resource exhaustion:

Resource exhaustion problems are often result due to an incorrect implementation of the following situations:

Potential Mitigations

• 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 is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/147.html
• https://cwe.mitre.org/data/definitions/227.html
• https://cwe.mitre.org/data/definitions/492.html

References

• https://git.kernel.org/stable/c/042a39bb8e0812466327a5102606e88a5a4f8c02
• https://git.kernel.org/stable/c/066afafc10c9476ee36c47c9062527a17e763901
• https://git.kernel.org/stable/c/0c38c9c460bb8ce8d6f6cf316e0d71a70983ec83
• https://git.kernel.org/stable/c/13857683126e8a6492af73c74d702835f7a2175b
• https://git.kernel.org/stable/c/87586467098281f04fa93e59fe3a516b954bddc4