UBUNTU-CVE-2024-26689

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UBUNTU-CVE-2024-26689

Summary:

Details: In the Linux kernel, the following vulnerability has been resolved: ceph: prevent use-after-free in encode_cap_msg() In fs/ceph/caps.c, in encode_cap_msg(), "use after free" error was caught by KASAN at this line - 'ceph_buffer_get(arg->xattr_buf);'. This implies before the refcount could be increment here, it was freed. In same file, in "handle_cap_grant()" refcount is decremented by this line - 'ceph_buffer_put(ci->i_xattrs.blob);'. It appears that a race occurred and resource was freed by the latter line before the former line could increment it. encode_cap_msg() is called by __send_cap() and __send_cap() is called by ceph_check_caps() after calling __prep_cap(). __prep_cap() is where arg->xattr_buf is assigned to ci->i_xattrs.blob. This is the spot where the refcount must be increased to prevent "use after free" error.

References: https://ubuntu.com/security/CVE-2024-26689, https://git.kernel.org/linus/cda4672da1c26835dcbd7aec2bfed954eda9b5ef, https://git.kernel.org/stable/c/8180d0c27b93a6eb60da1b08ea079e3926328214, https://git.kernel.org/stable/c/70e329b440762390258a6fe8c0de93c9fdd56c77, https://git.kernel.org/stable/c/f3f98d7d84b31828004545e29fd7262b9f444139, https://git.kernel.org/stable/c/ae20db45e482303a20e56f2db667a9d9c54ac7e7, https://git.kernel.org/stable/c/7958c1bf5b03c6f1f58e724dbdec93f8f60b96fc, https://git.kernel.org/stable/c/cda4672da1c26835dcbd7aec2bfed954eda9b5ef, https://www.cve.org/CVERecord?id=CVE-2024-26689, https://ubuntu.com/security/notices/USN-6766-1, https://ubuntu.com/security/notices/USN-6766-2, https://ubuntu.com/security/notices/USN-6766-3, https://ubuntu.com/security/notices/USN-6795-1, https://ubuntu.com/security/notices/USN-6828-1, https://ubuntu.com/security/notices/USN-6895-1, https://ubuntu.com/security/notices/USN-6895-2, https://ubuntu.com/security/notices/USN-6900-1, https://ubuntu.com/security/notices/USN-6895-3, https://ubuntu.com/security/notices/USN-6895-4, https://ubuntu.com/security/notices/USN-7495-1, https://ubuntu.com/security/notices/USN-7495-2, https://ubuntu.com/security/notices/USN-7496-1, https://ubuntu.com/security/notices/USN-7495-3, https://ubuntu.com/security/notices/USN-7496-3, https://ubuntu.com/security/notices/USN-7496-4, https://ubuntu.com/security/notices/USN-7496-5, https://ubuntu.com/security/notices/USN-7506-1, https://ubuntu.com/security/notices/USN-7506-2, https://ubuntu.com/security/notices/USN-7506-3, https://ubuntu.com/security/notices/USN-7506-4, https://ubuntu.com/security/notices/USN-7517-1, https://ubuntu.com/security/notices/USN-7518-1, https://ubuntu.com/security/notices/USN-7517-2, https://ubuntu.com/security/notices/USN-7517-3, https://ubuntu.com/security/notices/USN-7539-1, https://ubuntu.com/security/notices/USN-7540-1, https://ubuntu.com/security/notices/USN-7640-1, https://ubuntu.com/security/notices/USN-7986-1