UBUNTU-CVE-2026-52955

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UBUNTU-CVE-2026-52955

Summary:

Details: In the Linux kernel, the following vulnerability has been resolved: libceph: Fix potential out-of-bounds access in crush_decode() A message of type CEPH_MSG_OSD_MAP containing a crush map with at least one bucket has two fields holding the bucket algorithm. If the values in these two fields differ, an out-of-bounds access can occur. This is the case because the first algorithm field (alg) is used to allocate the correct amount of memory for a bucket of this type, while the second algorithm field inside the bucket (b->alg) is used in the subsequent processing. This patch fixes the issue by adding a check that compares alg and b->alg and aborts the processing in case they differ. Furthermore, b->alg is set to 0 in this case, because the destruction of the crush map also uses this field to determine the bucket type, which can again result in an out-of-bounds access when trying to free the memory pointed to by the fields of the bucket. To correctly free the memory allocated for the bucket in such a case, the corresponding call to kfree is moved from the algorithm-specific crush_destroy_bucket functions to the generic crush_destroy_bucket().

References: https://ubuntu.com/security/CVE-2026-52955, https://www.cve.org/CVERecord?id=CVE-2026-52955, https://git.kernel.org/linus/4c79fc2d598694bda845b46229c9d48b65042970, https://ubuntu.com/security/notices/USN-8566-1, https://ubuntu.com/security/notices/USN-8568-1, https://ubuntu.com/security/notices/USN-8569-1, https://ubuntu.com/security/notices/USN-8567-1, https://ubuntu.com/security/notices/USN-8574-1, https://ubuntu.com/security/notices/USN-8575-1, https://ubuntu.com/security/notices/USN-8576-1, https://ubuntu.com/security/notices/USN-8593-1, https://ubuntu.com/security/notices/USN-8574-2, https://ubuntu.com/security/notices/USN-8595-1, https://ubuntu.com/security/notices/USN-8596-1, https://ubuntu.com/security/notices/USN-8575-2, https://ubuntu.com/security/notices/USN-8576-2, https://ubuntu.com/security/notices/USN-8603-1, https://ubuntu.com/security/notices/USN-8595-2, https://ubuntu.com/security/notices/USN-8606-1, https://ubuntu.com/security/notices/USN-8607-1, https://ubuntu.com/security/notices/USN-8608-1, https://ubuntu.com/security/notices/USN-8609-1, https://ubuntu.com/security/notices/USN-8575-3, https://ubuntu.com/security/notices/USN-8610-1, https://ubuntu.com/security/notices/USN-8618-1, https://ubuntu.com/security/notices/USN-8574-3, https://ubuntu.com/security/notices/USN-8595-3, https://ubuntu.com/security/notices/USN-8619-1, https://ubuntu.com/security/notices/USN-8620-1, https://ubuntu.com/security/notices/USN-8620-2, https://ubuntu.com/security/notices/USN-8620-3, https://ubuntu.com/security/notices/USN-8620-4, https://ubuntu.com/security/notices/USN-8633-1, https://ubuntu.com/security/notices/USN-8634-1, https://ubuntu.com/security/notices/USN-8635-1, https://ubuntu.com/security/notices/USN-8633-2, https://ubuntu.com/security/notices/USN-8645-1, https://ubuntu.com/security/notices/USN-8662-1, https://ubuntu.com/security/notices/USN-8663-1, https://ubuntu.com/security/notices/USN-8664-1, https://ubuntu.com/security/notices/USN-8665-1, https://ubuntu.com/security/notices/USN-8666-1, https://ubuntu.com/security/notices/USN-8662-2, https://ubuntu.com/security/notices/USN-8667-1, https://ubuntu.com/security/notices/USN-8668-1, https://ubuntu.com/security/notices/USN-8666-2, https://ubuntu.com/security/notices/USN-8666-3, https://ubuntu.com/security/notices/USN-8715-1, https://ubuntu.com/security/notices/USN-8728-1, https://ubuntu.com/security/notices/USN-8748-1