CVE-2024-36883

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

net: fix out-of-bounds access in ops_init

net_alloc_generic is called by net_alloc, which is called without any locking. It reads max_gen_ptrs, which is changed under pernet_ops_rwsem. It is read twice, first to allocate an array, then to set s.len, which is later used to limit the bounds of the array access.

It is possible that the array is allocated and another thread is registering a new pernet ops, increments max_gen_ptrs, which is then used to set s.len with a larger than allocated length for the variable array.

Fix it by reading max_gen_ptrs only once in net_alloc_generic. If max_gen_ptrs is later incremented, it will be caught in net_assign_generic.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

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.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/0c3248bc708a7797be573214065cf908ff1f54c7
• https://git.kernel.org/stable/c/2d60ff5874aefd006717ca5e22ac1e25eac29c42
• https://git.kernel.org/stable/c/3cdc34d76c4f777579e28ad373979d36c030cfd3
• https://git.kernel.org/stable/c/7b0e64583eab8c1d896b47e5dd0bf2e7d86ec41f
• https://git.kernel.org/stable/c/9518b79bfd2fbf99fa9b7e8e36bcb1825e7ba030
• https://git.kernel.org/stable/c/a26ff37e624d12e28077e5b24d2b264f62764ad6
• https://git.kernel.org/stable/c/b6dbfd5bcc267a95a0bf1bf96af46243f96ec6cd
• https://git.kernel.org/stable/c/f4f94587e1bf87cb40ec33955a9d90148dd026ab
• https://git.kernel.org/stable/c/0c3248bc708a7797be573214065cf908ff1f54c7
• https://git.kernel.org/stable/c/2d60ff5874aefd006717ca5e22ac1e25eac29c42
• https://git.kernel.org/stable/c/3cdc34d76c4f777579e28ad373979d36c030cfd3
• https://git.kernel.org/stable/c/7b0e64583eab8c1d896b47e5dd0bf2e7d86ec41f
• https://git.kernel.org/stable/c/9518b79bfd2fbf99fa9b7e8e36bcb1825e7ba030
• https://git.kernel.org/stable/c/a26ff37e624d12e28077e5b24d2b264f62764ad6
• https://git.kernel.org/stable/c/b6dbfd5bcc267a95a0bf1bf96af46243f96ec6cd
• https://git.kernel.org/stable/c/f4f94587e1bf87cb40ec33955a9d90148dd026ab
• https://lists.debian.org/debian-lts-announce/2024/06/msg00019.html
• https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html
• https://security.netapp.com/advisory/ntap-20241018-0001/