CVE-2024-56662

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

acpi: nfit: vmalloc-out-of-bounds Read in acpi_nfit_ctl

Fix an issue detected by syzbot with KASAN:

BUG: KASAN: vmalloc-out-of-bounds in cmd_to_func drivers/acpi/nfit/ core.c:416 [inline] BUG: KASAN: vmalloc-out-of-bounds in acpi_nfit_ctl+0x20e8/0x24a0 drivers/acpi/nfit/core.c:459

The issue occurs in cmd_to_func when the call_pkg->nd_reserved2 array is accessed without verifying that call_pkg points to a buffer that is appropriately sized as a struct nd_cmd_pkg. This can lead to out-of-bounds access and undefined behavior if the buffer does not have sufficient space.

To address this, a check was added in acpi_nfit_ctl() to ensure that buf is not NULL and that buf_len is less than sizeof(*call_pkg) before accessing it. This ensures safe access to the members of call_pkg, including the nd_reserved2 array.

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/143f723e9eb4f0302ffb7adfdc7ef77eab3f68e0
• https://git.kernel.org/stable/c/212846fafb753a48e869e2a342fc1e24048da771
• https://git.kernel.org/stable/c/265e98f72bac6c41a4492d3e30a8e5fd22fe0779
• https://git.kernel.org/stable/c/616aa5f3c86e0479bcbb81e41c08c43ff32af637
• https://git.kernel.org/stable/c/bbdb3307f609ec4dc9558770f464ede01fe52aed
• https://git.kernel.org/stable/c/e08dc2dc3c3f7938df0e4476fe3e6fdec5583c1d