CVE-2026-52958

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

libceph: Fix potential out-of-bounds access in osdmap_decode()

When decoding osd_state and osd_weight from an incoming osdmap in osdmap_decode(), both are decoded for each osd, i.e., map->max_osd times. The ceph_decode_need() check only accounts for sizeof(*map->osd_weight) once. This can potentially result in an out-of-bounds memory access if the incoming message is corrupted such that the max_osd value exceeds the actual content of the osdmap message.

This patch fixes the issue by changing the corresponding part in the ceph_decode_need() check to account for map->max_osd*sizeof(*map->osd_weight).

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/0d2dd7e6bb74fd7712aa73457a4a821906c6863a
• https://git.kernel.org/stable/c/35d0ed82d03e5ee77ea4f31f20e29562a7721649
• https://git.kernel.org/stable/c/36a79759a288961b1ff28a68ec2d1f56f6848098
• https://git.kernel.org/stable/c/3f2575bb7f955d42569d96c3e04fa958a0dcf4b4
• https://git.kernel.org/stable/c/48df98d12b15360cd56af5c1f460307b340c1197
• https://git.kernel.org/stable/c/8713bbc4b2b9ad78f803978e54b7e49dd21bd9be
• https://git.kernel.org/stable/c/e7187f33c02488697ec0d01d82bf7a3f8deaba8f
• https://git.kernel.org/stable/c/ee933694645dac062d65fc2743f92bc06fa0db6b